Programs & Examples On #Apache cayenne

Apache Cayenne is an open source persistence framework, providing object-relational mapping (ORM) and remoting services.

Check empty string in Swift?

I can recommend add small extension to String or Array that looks like

extension Collection {
    public var isNotEmpty: Bool {
        return !self.isEmpty

With it you can write code that is easier to read. Compare this two lines

if !someObject.someParam.someSubParam.someString.isEmpty {}


if someObject.someParam.someSubParam.someString.isNotEmpty {}

It is easy to miss ! sign in the beginning of fist line.

Java Mouse Event Right Click

To avoid any ambiguity, use the utilities methods from SwingUtilities :

SwingUtilities.isLeftMouseButton(MouseEvent anEvent) SwingUtilities.isRightMouseButton(MouseEvent anEvent) SwingUtilities.isMiddleMouseButton(MouseEvent anEvent)

What's the meaning of exception code "EXC_I386_GPFLT"?

I'm seeing this error code in rotation crashes on Xcode 12.0 Beta 6, only on the iOS 14 simulator. It doesn't crash on my real device running iOS 13 though! So if you're running beta stuff and seeing rotation crashes in the simulator, maybe you just need to run on a real device with a non-beta iOS version.

Escape curly brace '{' in String.Format

Use double braces {{ or }} so your code becomes:

sb.AppendLine(String.Format("public {0} {1} {{ get; private set; }}", 
prop.Type, prop.Name));

// For prop.Type of "Foo" and prop.Name of "Bar", the result would be:
// public Foo Bar { get; private set; }

Bash script to run php script

#!/usr/bin/env bash
PHP=`which php`
$PHP /path/to/php/file.php

Test file upload using HTTP PUT method

If you're using PHP you can test your PUT upload using the code below:

#Initiate cURL object
$curl = curl_init();
#Set your URL
curl_setopt($curl, CURLOPT_URL, '');
#Indicate, that you plan to upload a file
curl_setopt($curl, CURLOPT_UPLOAD, true);
#Indicate your protocol
#Set flags for transfer
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_BINARYTRANSFER, 1);
#Disable header (optional)
curl_setopt($curl, CURLOPT_HEADER, false);
#Set HTTP method to PUT
curl_setopt($curl, CURLOPT_PUT, 1);
#Indicate the file you want to upload
curl_setopt($curl, CURLOPT_INFILE, fopen('path_to_file', 'rb'));
#Indicate the size of the file (it does not look like this is mandatory, though)
curl_setopt($curl, CURLOPT_INFILESIZE, filesize('path_to_file'));
#Only use below option on TEST environment if you have a self-signed certificate!!! On production this can cause security issues
#curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);

SQL query, if value is null then return 1

You can use a CASE statement.

    CASE WHEN currate.currentrate IS NULL THEN 1 ELSE currate.currentrate END
FROM ...

DataTable, How to conditionally delete rows

You could query the dataset and then loop the selected rows to set them as delete.

var rows = dt.Select("col1 > 5");
foreach (var row in rows)

... and you could also create some extension methods to make it easier ...

myTable.Delete("col1 > 5");

public static DataTable Delete(this DataTable table, string filter)
    return table;
public static void Delete(this IEnumerable<DataRow> rows)
    foreach (var row in rows)

How to print a list with integers without the brackets, commas and no quotes?

If you're using Python 3, or appropriate Python 2.x version with from __future__ import print_function then:

data = [7, 7, 7, 7]
print(*data, sep='')

Otherwise, you'll need to convert to string and print:

print ''.join(map(str, data))

how to open popup window using jsp or jquery?

Can be done with in jquery-

<link rel="stylesheet" href="" />
    <script src=""></script>
    <script src=""></script>
    <link rel="stylesheet" href="/resources/demos/style.css" />
    $(function() {
    $( "#dialog" ).dialog();

    <div id="dialog" title="Basic dialog">
    //your form layout

How to make war file in Eclipse

File -> Export -> Web -> WAR file

OR in Kepler follow as shown below :

enter image description here

How to import RecyclerView for Android L-preview

If you using the updated or 2018 Version for Android Studio...

compile ''

will give you an error with following message "Configuration 'compile' is obsolete and has been replaced with 'implementation' and 'api'. It will be removed at the end of 2018."

Try using this

implementation ''

CSS Background Image Not Displaying

You have to use a relative path in the URL. I think you made two folders in the root directory where your index.html resides. One is 'CSS' folder & another is 'img' folder.

Now, if you have to access 'img' folder in css files. So you have to go back once in root directory using "../" syntax. Then move to the 'img' folder using "../img" syntax. Then write the image name "../img/debut_dark.png".

body { 
    background: url("../img/debut_dark.png") repeat 0 0;

.c vs .cc vs. .cpp vs .hpp vs .h vs .cxx

Talking about .hpp extension, I find it useful when people are supposed to know that this header file contains C++ an not C, like using namespaces or template etc, by the moment they see the files, so they won't try to feed it to a C compiler! And I also like to name header files which contain not only declarations but implementations as well, as .hpp files. like header files including template classes. Although that's just my opinion and of course it's not supposed to be right! :)

How to execute a * .PY file from a * .IPYNB file on the Jupyter notebook?

the below lines would also work


C# "internal" access modifier when doing unit testing

Keep using private by default. If a member shouldn't be exposed beyond that type, it shouldn't be exposed beyond that type, even to within the same project. This keeps things safer and tidier - when you're using the object, it's clearer which methods you're meant to be able to use.

Having said that, I think it's reasonable to make naturally-private methods internal for test purposes sometimes. I prefer that to using reflection, which is refactoring-unfriendly.

One thing to consider might be a "ForTest" suffix:

internal void DoThisForTest(string name)

private void DoThis(string name)
    // Real implementation

Then when you're using the class within the same project, it's obvious (now and in the future) that you shouldn't really be using this method - it's only there for test purposes. This is a bit hacky, and not something I do myself, but it's at least worth consideration.

What's the difference between IFrame and Frame?

The only reasons I can think of are actually in the wiki article you referenced to mention a couple...

"The "Verified by Visa" system has drawn some criticism, since it is hard for users to differentiate between the legitimate Verified by Visa pop-up window or inline frame, and a fraudulent phishing site."

"as of 2008, most web browsers do not provide a simple way to check the security certificate for the contents of an iframe"

If you read the Criticism section in the article it details all the potential security flaws.

Otherwise the only difference is the fact that an IFrame is an inline frame and a Frame is part of a Frameset. Which means more layout problems than anything else!

Error: "Input is not proper UTF-8, indicate encoding !" using PHP's simplexml_load_string

If you download XML file and open it for example in Notepad++ you'll see that encoding is set to something else than UTF8 - I'v had the same problem with xml made myself, and it was just te encoding in the editor :)

String <?xml version="1.0" encoding="UTF-8"?> don't set up the encoding of the document, it's only info for validator or another resource.

Using MySQL with Entity Framework

It's been released - Get the MySQL connector for .Net v6.5 - this has support for [Entity Framework]

I was waiting for this the whole time, although the support is basic, works for most basic scenarios of db interaction. It also has basic Visual Studio integration.

UPDATE Starting with version 6.7, Connector/Net will no longer include the MySQL for Visual Studio integration. That functionality is now available in a separate product called MySQL for Visual Studio available using the MySQL Installer for Windows (see

What is the easiest way to ignore a JPA field during persistence?

To ignore a field, annotate it with @Transient so it will not be mapped by hibernate.
Source: Hibernate Annotations.

How do I import a CSV file in R?

You would use the read.csv function; for example:

dat = read.csv("spam.csv", header = TRUE)

You can also reference this tutorial for more details.

Note: make sure the .csv file to read is in your working directory (using getwd()) or specify the right path to file. If you want, you can set the current directory using setwd.

git ahead/behind info between master and branch?

With Git 2.5+, you now have another option to see ahead/behind for all branches which are configured to push to a branch.

git for-each-ref --format="%(push:track)" refs/heads

See more at "Viewing Unpushed Git Commits"

Remove an item from array using UnderscoreJS

Use Underscore _.reject():

arr = _.reject(arr, function(d){ return === 3; });

SVN checkout the contents of a folder, not the folder itself

svn co svn://path destination

To specify current directory, use a "." for your destination directory:

svn checkout file:///home/landonwinters/svn/waterproject/trunk .

Get ALL User Friends Using Facebook Graph API - Android

In v2.0 of the Graph API, calling /me/friends returns the person's friends who also use the app.

In addition, in v2.0, you must request the user_friends permission from each user. user_friends is no longer included by default in every login. Each user must grant the user_friends permission in order to appear in the response to /me/friends. See the Facebook upgrade guide for more detailed information, or review the summary below.

The /me/friendlists endpoint and user_friendlists permission are not what you're after. This endpoint does not return the users friends - its lets you access the lists a person has made to organize their friends. It does not return the friends in each of these lists. This API and permission is useful to allow you to render a custom privacy selector when giving people the opportunity to publish back to Facebook.

If you want to access a list of non-app-using friends, there are two options:

  1. If you want to let your people tag their friends in stories that they publish to Facebook using your App, you can use the /me/taggable_friends API. Use of this endpoint requires review by Facebook and should only be used for the case where you're rendering a list of friends in order to let the user tag them in a post.

  2. If your App is a Game AND your Game supports Facebook Canvas, you can use the /me/invitable_friends endpoint in order to render a custom invite dialog, then pass the tokens returned by this API to the standard Requests Dialog.

In other cases, apps are no longer able to retrieve the full list of a user's friends (only those friends who have specifically authorized your app using the user_friends permission).

For apps wanting allow people to invite friends to use an app, you can still use the Send Dialog on Web or the new Message Dialog on iOS and Android.

How can I delay a method call for 1 second?

Swift 2.x

let delayTime = dispatch_time(DISPATCH_TIME_NOW, Int64(1 * Double(NSEC_PER_SEC)))
 dispatch_after(delayTime, dispatch_get_main_queue()) {
 print("do some work")

Swift 3.x --&-- Swift 4

DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
    print("do some work")

or pass a escaping closure

func delay(seconds: Double, completion: @escaping()-> Void) {
    DispatchQueue.main.asyncAfter(deadline: .now() + seconds, execute: completion)

How to quit android application programmatically

Easy and simple way to quit from the application

Intent homeIntent = new Intent(Intent.ACTION_MAIN);

How to connect to remote Oracle DB with PL/SQL Developer?

I would recommend creating a TNSNAMES.ORA file. From your Oracle Client install directory, navigate to NETWORK\ADMIN. You may already have a file called TNSNAMES.ORA, if so edit it, else create it using your favorite text editor.

Next, simply add an entry like this:

    (ADDRESS = (PROTOCOL = TCP)(HOST = = 1521))

You can change MYDB to whatever you like, this is the identifier that applications will will use to find the database using the info from TNSNAMES.

Finally, login with MYDB as your database in PL/SQL Developer. It should automatically find the connection string in the TNSNAMES.ORA.

If that does not work, hit Help->About then click the icon with an "i" in it in the upper-lefthand corner. The fourth tab is the "TNS Names" tab, check it to confirm that it is loading the proper TNSNAMES.ORA file. If it is not, you may have multiple Oracle installations on your computer, and you will need to find the one that is in use.

Calculate date from week number

I have made a refined version of the proposed solution that is a simpler and parametrises the firstDayOfWeek:

public static DateTime GetFirstDayOfWeek(int year, int week, DayOfWeek firstDayOfWeek)
    return GetWeek1Day1(year, firstDayOfWeek).AddDays(7 * (week - 1));

public static DateTime GetWeek1Day1(int year, DayOfWeek firstDayOfWeek)
    DateTime date = new DateTime(year, 1, 1);

    // Move towards firstDayOfWeek
    date = date.AddDays(firstDayOfWeek - date.DayOfWeek);

    // Either 1 or 52 or 53
    int weekOfYear = CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(date, CalendarWeekRule.FirstFullWeek, firstDayOfWeek);

    // Move forwards 1 week if week is 52 or 53
    date = date.AddDays(7 * System.Math.Sign(weekOfYear - 1));

    return date;

org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject

You can first read the whole content of file into a String.

FileInputStream fileInputStream = null;
String data="";
StringBuffer stringBuffer = new StringBuffer("");
    fileInputStream=new FileInputStream(filename);
    int i;
    data = stringBuffer.toString();
catch(Exception e){

Now You will have the whole content into String ( data variable ).

JSONParser parser = new JSONParser();
org.json.simple.JSONArray jsonArray= (org.json.simple.JSONArray) parser.parse(data);

After that you can use jsonArray as you want.

PHP Fatal error: Call to undefined function json_decode()

The module was install but symbolic link was not in /etc/php5/cli/conf.d

Python display text with font & color?

You can use your own custom fonts by setting the font path using pygame.font.Font

pygame.font.Font(filename, size): return Font


font_path = "./fonts/newfont.ttf"
font_size = 32
fontObj = pygame.font.Font(font_path, font_size)

Then render the font using fontObj.render and blit to a surface as in veiset's answer above. :)

get specific row from spark dataframe

There is a scala way (if you have a enough memory on working machine):

val arr ="column").rdd.collect

If dataframe schema is unknown, and you know actual type of "column" field (for example double), than you can get arr as following:

val arr =$"column".cast("Double")).as[Double].rdd.collect

delete all record from table in mysql

It’s because you tried to update a table without a WHERE that uses a KEY column.

The quick fix is to add SET SQL_SAFE_UPDATES=0; before your query :



close the safe update mode. Edit -> Preferences -> SQL Editor -> SQL Editor remove Forbid UPDATE and DELETE statements without a WHERE clause (safe updates) .

BTW you can use TRUNCATE TABLE tablename; to delete all the records .

Oracle get previous day records

Simple solution and understanding

To answer the question:

SELECT field,datetime_field 
FROM database

Some explanation

If you have a field that is not in date format but want to compare using date i.e. field is considered as date but in number format e.g. 20190823 (YYYYMMDD)


If you have a field that is in date/timestamp format and you need to compare, Just change the format


IF you want to return it to date format



With this knowledge you can convert the filed you want to compare to a YYYYMMDD or YYYY-MM-DD or any year-month-date format then compare with the same sysdate format.

Static Final Variable in Java

Just having final will have the intended effect.

final int x = 5;

x = 10; // this will cause a compilation error because x is final

Declaring static is making it a class variable, making it accessible using the class name <ClassName>.x

Finish an activity from another activity

First call startactivity() then use finish()

Oracle SQL - select within a select (on the same table!)

This is something I'd use the LAG function for:

SELECT eh.gc_staff_number,
       LAG(eh.end_date) OVER (PARTITION BY eh.gc_staff_number
                                  ORDER BY eh.end_date) AS prev_end_date
 WHERE eh.current_flag = 'Y'

If you wanted to peek a row ahead, you'd use the LEAD function.


To my knowledge, this is supported 9i+ but I haven't confirmed that 8i is supported like the documentation claims.

LEAD and LAG are finally ANSI, but only Oracle and PostgreSQL v8.4+ support them currently.

How to define a default value for "input type=text" without using attribute 'value'?

You can set the value property using client script after the element is created:

<input type="text" id="fee" />

<script type="text/javascript>
document.getElementById('fee').value = '1000';

When to use reinterpret_cast?

template <class outType, class inType>
outType safe_cast(inType pointer)
    void* temp = static_cast<void*>(pointer);
    return static_cast<outType>(temp);

I tried to conclude and wrote a simple safe cast using templates. Note that this solution doesn't guarantee to cast pointers on a functions.

How to change css property using javascript

var hello = $('.right') // or var hello = document.getElementByClassName('right')
var bye = $('.right1')
hello.onmouseover = function()
{ = 'visible'
hello.onmouseout = function()
{ = 'hidden'

How to have a a razor action link open in a new tab?

"Pay Now",
new { @id = 1 },htmlAttributes:new { @class="btn btn-success",@target= "_blank" } )

How do I use StringUtils in Java?

StringUtils is part of Apache Commons Lang (, and as the name suggest it provides some nice utilities for dealing with Strings, going beyond what is offered in java.lang.String. It consists of over 50 static methods.

There are two different versions available, the newer org.apache.commons.lang3.StringUtils and the older org.apache.commons.lang.StringUtils. There are not really any significant differences between the two. lang3.StringUtils requires Java 5.0 and is probably the version you'll want to use.

const to Non-const Conversion in C++

Leaving this here for myself,

If I get this error, I probably used const char* when I should be using char* const.

This makes the pointer constant, and not the contents of the string.

const char* const makes it so the value and the pointer is constant also.

Define a struct inside a class in C++

using namespace std;

class A
        struct Assign
                int a=10;
                float b=20.5;
                double c=30.0;
                long int d=40;
         struct Assign ALT;

class B: public A
    int x = 10;
    float y = 20.8;

int main()
   B myobj;
   A obj;

    return 0;

    enter code here

How to get file's last modified date on Windows command line?

To get the last modification date/time of a file in a locale-independent manner you could use the wmic command with the DataFile alias:

wmic DataFile where "Name='D:\\Path\\To\\myfile.txt'" get LastModified /VALUE

Regard that the full path to the file must be provided and that all path separators (backslashes \) must be doubled herein.

This returns a standardised date/time value like this (meaning 12th of August 2019, 13:00:00, UTC + 120'):


To capture the date/time value use for /F, then you can assign it to a variable using set:

for /F "delims=" %%I in ('
    wmic DataFile where "Name='D:\\Path\\To\\myfile.txt'" get LastModified /VALUE
') do for /F "tokens=1* delims==" %%J in ("%%I") do set "DateTime=%%K"

The second for /F loop avoids artefacts (like orphaned carriage-return characters) from conversion of the Unicode output of wmic to ASCII/ANSI text by the first for /F loop (see also this answer).

You can then use sub-string expansion to extract the pure date or the time from this:

set "DateOnly=%DateTime:~0,8%"
set "TimeOnly=%DateTime:~8,6%"

To get the creation date/time or the last access date/time, just replace the property LastModified by CreationDate or LastAccessed, respectively. To get information about a directory rather than a file, use the alias FSDir instead of DataFile.

For specifying file (or directory) paths/names containing both , and ), which are usually not accepted by wmic, take a look at this question.

Check out also this post as well as this one about how to get file and directory date/time stamps.

How to enable C++11/C++0x support in Eclipse CDT?

To get support for C++14 in Eclipse Luna, you could do these steps:

  • In C++ General -> Preprocessor Include -> Providers -> CDT Cross GCC Built-in Compiler Settings, add "-std=c++14"
  • In C++ Build -> Settings -> Cross G++ Compiler -> Miscellaneous, add "-std=c++14"

Reindex your project and eventually restart Eclipse. It should work as expected.

Laravel Escaping All HTML in Blade Template

There is no problem with displaying HTML code in blade templates.

For test, you can add to routes.php only one route:

Route::get('/', function () {

        $data = new stdClass();
            = '<strong>aaa</strong><em>bbb</em>
               <p>New paragaph</p><script>alert("Hello");</script>';

        return View::make('hello')->with('content', $data);

and in hello.blade.php file:

<!doctype html>
<html lang="en">
    <meta charset="UTF-8">

{{ $content->page_desc }}


For the following code you will get output as on image


So probably page_desc in your case is not what you expect. But as you see it can be potential dangerous if someone uses for example '` tag so you should probably in your route before assigning to blade template filter some tags


I've also tested it with putting the same code into database:

Route::get('/', function () {

        $data = User::where('id','=',1)->first();

        return View::make('hello')->with('content', $data);

Output is exactly the same in this case


I also don't know if Pages is your model or it's a vendor model. For example it can have accessor inside:

public function getPageDescAttribute($value)
    return htmlspecialchars($value);

and then when you get page_desc attribute you will get modified page_desc with htmlspecialchars. So if you are sure that data in database is with raw html (not escaped) you should look at this Pages class

Run local java applet in browser (chrome/firefox) "Your security settings have blocked a local application from running"

just add your .jar file in applet tag as an attribute as shown below:


Android Device not recognized by adb

For those people to whom none of the answers worked.... try closing the chrome://inspect/#devices tab in chrome if opened... This worked for me.

jquery.ajax Access-Control-Allow-Origin

refer the above link for more details on Cross domain resource sharing.

you can try using JSONP . If the API is not supporting jsonp, you have to create a service which acts as a middleman between the API and your client. In my case, i have created a asmx service.

sample below:

ajax call:

$(document).ready(function () {
            crossDomain: true,
            contentType: "application/json; charset=utf-8",
            url: "<your middle man service url here>/GetQuote?callback=?",
            data: { symbol: 'ctsh' },
            dataType: "jsonp",                
            jsonpCallback: 'fnsuccesscallback'

service (asmx) which will return jsonp:

    [ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
    public void GetQuote(String symbol,string callback)

        WebProxy myProxy = new WebProxy("<proxy url here>", true);

        myProxy.Credentials = new System.Net.NetworkCredential("username", "password", "domain");
        StockQuoteProxy.StockQuote SQ = new StockQuoteProxy.StockQuote();
        SQ.Proxy = myProxy;
        String result = SQ.GetQuote(symbol);
        StringBuilder sb = new StringBuilder();
        JavaScriptSerializer js = new JavaScriptSerializer();
        sb.Append(callback + "(");
        Context.Response.ContentType = "application/json";

Make hibernate ignore class variables that are not mapped

Placing @Transient on getter with private field worked for me.

private String name;

    public String getName() {
        return name;

    public void setName(String name) { = name;

"ImportError: no module named 'requests'" after installing with pip

In Windows it worked for me only after trying the following: 1. Open cmd inside the folder where "requests" is unpacked. (CTRL+SHIFT+right mouse click, choose the appropriate popup menu item) 2. (Here is the path to your pip3.exe)\pip3.exe install requests Done

How to use FormData in react-native?

Here is my simple code FormData with react-native to post request with string and image.

I have used react-native-image-picker to capture/select photo react-native-image-picker

let photo = { uri: source.uri}
let formdata = new FormData();

formdata.append("product[name]", 'test')
formdata.append("product[price]", 10)
formdata.append("product[category_ids][]", 2)
formdata.append("product[description]", '12dsadadsa')
formdata.append("product[images_attributes[0][file]]", {uri: photo.uri, name: 'image.jpg', type: 'image/jpeg'})

NOTE you can change image/jpeg to other content type. You can get content type from image picker response.

  method: 'post',
  headers: {
    'Content-Type': 'multipart/form-data',
  body: formdata
  }).then(response => {
    console.log("image uploaded")
  }).catch(err => {

Enum Naming Convention - Plural

Coming in a bit late...

There's an important difference between your question and the one you mention (which I asked ;-):

You put the enum definition out of the class, which allows you to have the same name for the enum and the property:

public enum EntityType { 
  Type1, Type2 

public class SomeClass { 
  public EntityType EntityType {get; set;} // This is legal


In this case, I'd follow the MS guidelins and use a singular name for the enum (plural for flags). It's probaby the easiest solution.

My problem (in the other question) is when the enum is defined in the scope of the class, preventing the use of a property named exactly after the enum.

Python extending with - using super() Python 3 vs Python 2

Just to have a simple and complete example for Python 3, which most people seem to be using now.

class MySuper(object):
    def __init__(self,a):
        self.a = a

class MySub(MySuper):
    def __init__(self,a,b):
        self.b = b

my_sub = MySub(42,'chickenman')



Populating a data frame in R in a loop

You could do it like this:

 iterations = 10
 variables = 2

 output <- matrix(ncol=variables, nrow=iterations)

 for(i in 1:iterations){
  output[i,] <- runif(2)



and then turn it into a data.frame

 output <- data.frame(output)

what this does:

  1. create a matrix with rows and columns according to the expected growth
  2. insert 2 random numbers into the matrix
  3. convert this into a dataframe after the loop has finished.

What is the easiest way to parse an INI file in Java?

It is just as simple as this.....


Properties prop = new Properties();
//c:\\myapp\\config.ini is the location of the ini file
//ini file should look like host=localhost
prop.load(new FileInputStream("c:\\myapp\\config.ini"));
String host = prop.getProperty("host");

Pytorch reshape tensor dimension

or you can use this, the '-1' means you don't have to specify the number of the elements.

In [3]: a.view(1,-1)

 1  2  3  4  5
[torch.FloatTensor of size 1x5]

Assign result of dynamic sql to variable

You can use sp_executesql with output parameter.

declare @S nvarchar(max) = 'select @x = 1'

declare @xx int
set @xx = 0

exec sp_executesql @S, N'@x int out', @xx out

select @xx


(No column name)


In my sample @S is instead of your @template. As you can see I assign a value to @x so you need to modify @template so it internally assigns the comma separated string to the variable you define in your second argument to sp_executesql. In my sample N'@x int out'. You probably want a varchar(max) output parameter. Something like N'@Result varchar(max) out'

Here is another example building a comma separated string from master..spt_values

declare @template nvarchar(max)
set @template = 
'select @Result += cast(number as varchar(10))+'',''
from master..spt_values
where type = ''P''

declare @CommaString varchar(max)
set @CommaString = ''

exec sp_executesql @template, N'@Result varchar(max) out', @CommaString out

select @CommaString

Creating table variable in SQL server 2008 R2

@tableName Table variables are alive for duration of the script running only i.e. they are only session level objects.

To test this, open two query editor windows under sql server management studio, and create table variables with same name but different structures. You will get an idea. The @tableName object is thus temporary and used for our internal processing of data, and it doesn't contribute to the actual database structure.

There is another type of table object which can be created for temporary use. They are #tableName objects declared like similar create statement for physical tables:

Create table #test (Id int, Name varchar(50))

This table object is created and stored in temp database. Unlike the first one, this object is more useful, can store large data and takes part in transactions etc. These tables are alive till the connection is open. You have to drop the created object by following script before re-creating it.

IF OBJECT_ID('tempdb..#test') IS NOT NULL
  DROP TABLE #test 

Hope this makes sense !

The SQL OVER() clause - when and why is it useful?

So in simple words: Over clause can be used to select non aggregated values along with Aggregated ones.

Partition BY, ORDER BY inside, and ROWS or RANGE are part of OVER() by clause.

partition by is used to partition data and then perform these window, aggregated functions, and if we don't have partition by the then entire result set is considered as a single partition.

OVER clause can be used with Ranking Functions(Rank, Row_Number, Dense_Rank..), Aggregate Functions like (AVG, Max, Min, SUM...etc) and Analytics Functions like (First_Value, Last_Value, and few others).

Let's See basic syntax of OVER clause

OVER (   
       [ <PARTITION BY clause> ]  
       [ <ORDER BY clause> ]   
       [ <ROW or RANGE clause> ]  

PARTITION BY: It is used to partition data and perform operations on groups with the same data.

ORDER BY: It is used to define the logical order of data in Partitions. When we don't specify Partition, entire resultset is considered as a single partition

: This can be used to specify what rows are supposed to be considered in a partition when performing the operation.

Let's take an example:

Here is my dataset:

Id          Name                                               Gender     Salary
----------- -------------------------------------------------- ---------- -----------
1           Mark                                               Male       5000
2           John                                               Male       4500
3           Pavan                                              Male       5000
4           Pam                                                Female     5500
5           Sara                                               Female     4000
6           Aradhya                                            Female     3500
7           Tom                                                Male       5500
8           Mary                                               Female     5000
9           Ben                                                Male       6500
10          Jodi                                               Female     7000
11          Tom                                                Male       5500
12          Ron                                                Male       5000

So let me execute different scenarios and see how data is impacted and I'll come from difficult syntax to simple one

Select *,SUM(salary) Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        32000
1           Mark                                               Male       5000        32000
8           Mary                                               Female     5000        32000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        48500
7           Tom                                                Male       5500        48500
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

Just observe the sum_sal part. Here I am using order by Salary and using "RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW". In this case, we are not using partition so entire data will be treated as one partition and we are ordering on salary. And the important thing here is UNBOUNDED PRECEDING AND CURRENT ROW. This means when we are calculating the sum, from starting row to the current row for each row. But if we see rows with salary 5000 and name="Pavan", ideally it should be 17000 and for salary=5000 and name=Mark, it should be 22000. But as we are using RANGE and in this case, if it finds any similar elements then it considers them as the same logical group and performs an operation on them and assigns value to each item in that group. That is the reason why we have the same value for salary=5000. The engine went up to salary=5000 and Name=Ron and calculated sum and then assigned it to all salary=5000.

Select *,SUM(salary) Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

   Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        17000
1           Mark                                               Male       5000        22000
8           Mary                                               Female     5000        27000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        37500
7           Tom                                                Male       5500        43000
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

So with ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW The difference is for same value items instead of grouping them together, It calculates SUM from starting row to current row and it doesn't treat items with same value differently like RANGE

Select *,SUM(salary) Over(order by salary) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
6           Aradhya                                            Female     3500        3500
5           Sara                                               Female     4000        7500
2           John                                               Male       4500        12000
3           Pavan                                              Male       5000        32000
1           Mark                                               Male       5000        32000
8           Mary                                               Female     5000        32000
12          Ron                                                Male       5000        32000
11          Tom                                                Male       5500        48500
7           Tom                                                Male       5500        48500
4           Pam                                                Female     5500        48500
9           Ben                                                Male       6500        55000
10          Jodi                                               Female     7000        62000

These results are the same as

Select *, SUM(salary) Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as sum_sal from employees

That is because Over(order by salary) is just a short cut of Over(order by salary RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) So wherever we simply specify Order by without ROWS or RANGE it is taking RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW as default.

Note: This is applicable only to Functions that actually accept RANGE/ROW. For example, ROW_NUMBER and few others don't accept RANGE/ROW and in that case, this doesn't come into the picture.

Till now we saw that Over clause with an order by is taking Range/ROWS and syntax looks something like this RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW And it is actually calculating up to the current row from the first row. But what If it wants to calculate values for the entire partition of data and have it for each column (that is from 1st row to last row). Here is the query for that

Select *,sum(salary) Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
1           Mark                                               Male       5000        62000
2           John                                               Male       4500        62000
3           Pavan                                              Male       5000        62000
4           Pam                                                Female     5500        62000
5           Sara                                               Female     4000        62000
6           Aradhya                                            Female     3500        62000
7           Tom                                                Male       5500        62000
8           Mary                                               Female     5000        62000
9           Ben                                                Male       6500        62000
10          Jodi                                               Female     7000        62000
11          Tom                                                Male       5500        62000
12          Ron                                                Male       5000        62000

Instead of CURRENT ROW, I am specifying UNBOUNDED FOLLOWING which instructs the engine to calculate till the last record of partition for each row.

Now coming to your point on what is OVER() with empty braces?

It is just a short cut for Over(order by salary ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)

Here we are indirectly specifying to treat all my resultset as a single partition and then perform calculations from the first record to the last record of each partition.

Select *,Sum(salary) Over() as sum_sal from employees

Id          Name                                               Gender     Salary      sum_sal
----------- -------------------------------------------------- ---------- ----------- -----------
1           Mark                                               Male       5000        62000
2           John                                               Male       4500        62000
3           Pavan                                              Male       5000        62000
4           Pam                                                Female     5500        62000
5           Sara                                               Female     4000        62000
6           Aradhya                                            Female     3500        62000
7           Tom                                                Male       5500        62000
8           Mary                                               Female     5000        62000
9           Ben                                                Male       6500        62000
10          Jodi                                               Female     7000        62000
11          Tom                                                Male       5500        62000
12          Ron                                                Male       5000        62000

I did create a video on this and if you are interested you can visit it.

Thanks, Pavan Kumar Aryasomayajulu HTTP://

In Unix, how do you remove everything in the current directory and below it?

Practice safe computing. Simply go up one level in the hierarchy and don't use a wildcard expression:

cd ..; rm -rf -- <dir-to-remove>

The two dashes -- tell rm that <dir-to-remove> is not a command-line option, even when it begins with a dash.

ORA-01461: can bind a LONG value only for insert into a LONG column-Occurs when querying

I encountered this error message when trying to insert String into an XMLTYPE column.

Specifically using Java's PreparedStatement like this:

ps.setString('XML', document);

where XML here is defined as XMLTYPE.

What is the best way to ensure only one instance of a Bash script is running?

If the script is the same across all users, you can use a lockfile approach. If you acquire the lock, proceed else show a message and exit.

As an example:

[Terminal #1] $ lockfile -r 0 /tmp/the.lock
[Terminal #1] $ 

[Terminal #2] $ lockfile -r 0 /tmp/the.lock
[Terminal #2] lockfile: Sorry, giving up on "/tmp/the.lock"

[Terminal #1] $ rm -f /tmp/the.lock
[Terminal #1] $ 

[Terminal #2] $ lockfile -r 0 /tmp/the.lock
[Terminal #2] $ 

After /tmp/the.lock has been acquired your script will be the only one with access to execution. When you are done, just remove the lock. In script form this might look like:


lockfile -r 0 /tmp/the.lock || exit 1

# Do stuff here

rm -f /tmp/the.lock

Chrome Uncaught Syntax Error: Unexpected Token ILLEGAL

I had the same error when multiline string included new line (\n) characters. Merging all lines into one (thus removing all new line characters) and sending it to a browser used to solve. But was very inconvenient to code.

Often could not understand why this was an issue in Chrome until I came across to a statement which said that the current version of JavaScript engine in Chrome doesn't support multiline strings which are wrapped in single quotes and have new line (\n) characters in them. To make it work, multiline string need to be wrapped in double quotes. Changing my code to this, resolved this issue.

I will try to find a reference to a standard or Chrome doc which proves this. Until then, try this solution and see if works for you as well.

How to repair a serialized string which has been corrupted by an incorrect byte count length?

There's another reason unserialize() failed because you improperly put serialized data into the database see Official Explanation here. Since serialize() returns binary data and php variables don't care encoding methods, so that putting it into TEXT, VARCHAR() will cause this error.

Solution: store serialized data into BLOB in your table.

When should I use cross apply over inner join?

Here's a brief tutorial that can be saved in a .sql file and executed in SSMS that I wrote for myself to quickly refresh my memory on how CROSS APPLY works and when to use it:

-- Here's the key to understanding CROSS APPLY: despite the totally different name, think of it as being like an advanced 'basic join'.
-- A 'basic join' gives the Cartesian product of the rows in the tables on both sides of the join: all rows on the left joined with all rows on the right.
-- The formal name of this join in SQL is a CROSS JOIN.  You now start to understand why they named the operator CROSS APPLY.

-- Given the following (very) simple tables and data:
CREATE TABLE #TempStrings ([SomeString] [nvarchar](10) NOT NULL);
CREATE TABLE #TempNumbers ([SomeNumber] [int] NOT NULL);
CREATE TABLE #TempNumbers2 ([SomeNumber] [int] NOT NULL);
INSERT INTO #TempStrings VALUES ('111'); INSERT INTO #TempStrings VALUES ('222');
INSERT INTO #TempNumbers VALUES (111); INSERT INTO #TempNumbers VALUES (222);
INSERT INTO #TempNumbers2 VALUES (111); INSERT INTO #TempNumbers2 VALUES (222); INSERT INTO #TempNumbers2 VALUES (222);

-- Basic join is like CROSS APPLY; 2 rows on each side gives us an output of 4 rows, but 2 rows on the left and 0 on the right gives us an output of 0 rows:
    st.SomeString, nbr.SomeNumber
FROM -- Basic join ('CROSS JOIN')
    #TempStrings st, #TempNumbers nbr
    -- Note: this also works:
    --#TempStrings st CROSS JOIN #TempNumbers nbr

-- Basic join can be used to achieve the functionality of INNER JOIN by first generating all row combinations and then whittling them down with a WHERE clause:
    st.SomeString, nbr.SomeNumber
FROM -- Basic join ('CROSS JOIN')
    #TempStrings st, #TempNumbers nbr
    st.SomeString = nbr.SomeNumber

-- However, for increased readability, the SQL standard introduced the INNER JOIN ... ON syntax for increased clarity; it brings the columns that two tables are
-- being joined on next to the JOIN clause, rather than having them later on in the WHERE clause.  When multiple tables are being joined together, this makes it
-- much easier to read which columns are being joined on which tables; but make no mistake, the following syntax is *semantically identical* to the above syntax:
    st.SomeString, nbr.SomeNumber
FROM -- Inner join
    #TempStrings st INNER JOIN #TempNumbers nbr ON st.SomeString = nbr.SomeNumber

-- Because CROSS APPLY is generally used with a subquery, the subquery's WHERE clause will appear next to the join clause (CROSS APPLY), much like the aforementioned
-- 'ON' keyword appears next to the INNER JOIN clause.  In this sense, then, CROSS APPLY combined with a subquery that has a WHERE clause is like an INNER JOIN with
-- an ON keyword, but more powerful because it can be used with subqueries (or table-valued functions, where said WHERE clause can be hidden inside the function).
    st.SomeString, nbr.SomeNumber
    #TempStrings st CROSS APPLY (SELECT * FROM #TempNumbers tempNbr WHERE st.SomeString = tempNbr.SomeNumber) nbr

-- CROSS APPLY joins in the same way as a CROSS JOIN, but what is joined can be a subquery or table-valued function.  You'll still get 0 rows of output if
-- there are 0 rows on either side, and in this sense it's like an INNER JOIN:
    st.SomeString, nbr.SomeNumber
    #TempStrings st CROSS APPLY (SELECT * FROM #TempNumbers tempNbr WHERE 1 = 2) nbr

-- OUTER APPLY is like CROSS APPLY, except that if one side of the join has 0 rows, you'll get the values of the side that has rows, with NULL values for
-- the other side's columns.  In this sense it's like a FULL OUTER JOIN:
    st.SomeString, nbr.SomeNumber
    #TempStrings st OUTER APPLY (SELECT * FROM #TempNumbers tempNbr WHERE 1 = 2) nbr

-- One thing CROSS APPLY makes it easy to do is to use a subquery where you would usually have to use GROUP BY with aggregate functions in the SELECT list.
-- In the following example, we can get an aggregate of string values from a second table based on matching one of its columns with a value from the first
-- table - something that would have had to be done in the ON clause of the LEFT JOIN - but because we're now using a subquery thanks to CROSS APPLY, we
-- don't need to worry about GROUP BY in the main query and so we don't have to put all the SELECT values inside an aggregate function like MIN().
    st.SomeString, nbr.SomeNumbers
    #TempStrings st CROSS APPLY (SELECT SomeNumbers = STRING_AGG(tempNbr.SomeNumber, ', ') FROM #TempNumbers2 tempNbr WHERE st.SomeString = tempNbr.SomeNumber) nbr
-- ^ First the subquery is whittled down with the WHERE clause, then the aggregate function is applied with no GROUP BY clause; this means all rows are
--   grouped into one, and the aggregate function aggregates them all, in this case building a comma-delimited string containing their values.

DROP TABLE #TempStrings;
DROP TABLE #TempNumbers;
DROP TABLE #TempNumbers2;

How to set radio button checked as default in radiogroup?

you should check the radiobutton in the radiogroup like this:


Of course you first have to set an Id to your radiobuttons

EDIT: i forgot, radioButton.getId() works as well, thx Ramesh



works in radiogroup xml

How to get the hostname of the docker host from inside a docker container on that host without env vars

You can easily pass it as an environment variable

docker run .. -e HOST_HOSTNAME=`hostname` ..


-e HOST_HOSTNAME=`hostname`

will call the hostname and use it's return as an environment variable called HOST_HOSTNAME, of course you can customize the key as you like.

note that this works on bash shell, if you using a different shell you might need to see the alternative for "backtick", for example a fish shell alternative would be

docker run .. -e HOST_HOSTNAME=(hostname) ..

Angular ReactiveForms: Producing an array of checkbox values?

Related answer to @nash11, here's how you would produce an array of checkbox values


have a checkbox that also selectsAll the checkboxes:

Get last key-value pair in PHP array

If you have an array

$last_element = array_pop(array);

How should I multiple insert multiple records?

Stored procedure to insert multiple records using single insertion:

@i varchar(50),
@n varchar(50),
@a varchar(50),
@i1 varchar(50),
@n1 varchar(50),
@a1 varchar(50),
@i2 varchar(50),
@n2 varchar(50),
@a2 varchar(50) 
SELECT     @i AS Expr1, @i1 AS Expr2, @i2 AS Expr3
SELECT     @n AS Expr1, @n1 AS Expr2, @n2 AS Expr3
SELECT     @a AS Expr1, @a1 AS Expr2, @a2 AS Expr3

Code behind:

protected void Button1_Click(object sender, EventArgs e)
    SqlCommand cmd = new SqlCommand("Ins",cn);
    cmd.CommandType = CommandType.StoredProcedure;

Compile a DLL in C/C++, then call it from another program

Here is how you do it:

In .h

#ifdef BUILD_DLL
#define EXPORT __declspec(dllexport)
#define EXPORT __declspec(dllimport)

extern "C" // Only if you are using C++ rather than C
  EXPORT int __stdcall add2(int num);
  EXPORT int __stdcall mult(int num1, int num2);

in .cpp

extern "C" // Only if you are using C++ rather than C
EXPORT int __stdcall add2(int num)
  return num + 2;

EXPORT int __stdcall mult(int num1, int num2)
  int product;
  product = num1 * num2;
  return product;

The macro tells your module (i.e your .cpp files) that they are providing the dll stuff to the outside world. People who incude your .h file want to import the same functions, so they sell EXPORT as telling the linker to import. You need to add BUILD_DLL to the project compile options, and you might want to rename it to something obviously specific to your project (in case a dll uses your dll).

You might also need to create a .def file to rename the functions and de-obfuscate the names (C/C++ mangles those names). This blog entry might be an interesting launching off point about that.

Loading your own custom dlls is just like loading system dlls. Just ensure that the DLL is on your system path. C:\windows\ or the working dir of your application are an easy place to put your dll.

How can I wait for 10 second without locking application UI in android

1with handler:

handler.sendEmptyMessageDelayed(1, 10000);

private Handler handler = new Handler() {
    public void handleMessage(Message msg) {
        if (msg.what == 1) {
           //your code

Use 'import module' or 'from module import'?

As Jan Wrobel mentions, one aspect of the different imports is in which way the imports are disclosed.

Module mymath

from math import gcd

Use of mymath:

import mymath
mymath.gcd(30, 42)  # will work though maybe not expected

If I imported gcd only for internal use, not to disclose it to users of mymath, this can be inconvenient. I have this pretty often, and in most cases I want to "keep my modules clean".

Apart from the proposal of Jan Wrobel to obscure this a bit more by using import math instead, I have started to hide imports from disclosure by using a leading underscore:

# for instance...
from math import gcd as _gcd
# or...
import math as _math

In larger projects this "best practice" allows my to exactly control what is disclosed to subsequent imports and what isn't. This keeps my modules clean and pays back at a certain size of project.

How to set background color of a View

You made your button transparent. The first byte is the alpha.

Try v.setBackgroundColor(0xFF00FF00);

How do you delete all text above a certain line

d1G = delete to top including current line (vi)

Spring Data JPA - "No Property Found for Type" Exception

If you are using a composite key in your bean, your parameter will be an object. You need to adjust your findBy method according to the new combination.

public class CombinationId implements Serializable {

  private String xId;
  private String yId;

public class RealObject implements Serializable, Persistable<CombinationId> {

  @EmbeddedId private CombinationId id;

In that case, your repository findBy method should be as this

public interface PaymentProfileRepository extends JpaRepository<RealObject, String> {

  List<RealObject> findById_XId(String someString);

ADB not recognising Nexus 4 under Windows 7

I had the same problem and none of the above worked, but the following solution worked for me:

On my Nexus 4:

  • Go to Settings

  • Choose Developer options (from the end of the list after pressing seven times on "About phone")

  • Check the "USB debugging" and press OK.

Executing a command stored in a variable from PowerShell

Here is yet another way without Invoke-Expression but with two variables (command:string and parameters:array). It works fine for me. Assume 7z.exe is in the system path.

$cmd = '7z.exe'
$prm = 'a', '-tzip', 'c:\temp\with space\', 'C:\TEMP\with space\changelog'

& $cmd $prm

If the command is known (7z.exe) and only parameters are variable then this will do

$prm = 'a', '-tzip', 'c:\temp\with space\', 'C:\TEMP\with space\changelog'

& 7z.exe $prm

BTW, Invoke-Expression with one parameter works for me, too, e.g. this works

$cmd = '& 7z.exe a -tzip "c:\temp\with space\" "C:\TEMP\with space\changelog"'

Invoke-Expression $cmd

P.S. I usually prefer the way with a parameter array because it is easier to compose programmatically than to build an expression for Invoke-Expression.

How to set conditional breakpoints in Visual Studio?

Writing the actual condition can be the tricky part, so I tend to

  1. Set a regular breakpoint.
  2. Run the code until the breakpoint is hit for the first time.
  3. Use the Immediate Window (Debug > Windows > Immediate) to test your expression.
  4. Right-click the breakpoint, click Condition and paste in your expression.

Advantages of using the Immediate window:

  • It has IntelliSense.
  • You can be sure that the variables in the expression are in scope when the expression is evaluated.
  • You can be sure your expression returns true or false.

This example breaks when the code is referring to a table with the name "Setting":


Disabling buttons on react native

To disable Text you have to set the opacity:0 in Text style like this:

<TouchableOpacity style={{opacity:0}}>
  <Text>I'm disabled</Text>


You can use SEPARATOR and ORDER BY inside the GROUP_CONCAT function in this way:

SELECT li.client_id, group_concat(li.percentage ORDER BY li.views ASC SEPARATOR ',') 
AS views, group_concat(li.percentage ORDER BY li.percentage ASC SEPARATOR ',') FROM li
GROUP BY client_id;

Android Studio : unmappable character for encoding UTF-8

I have the problem with encoding in javadoc generated by intellij idea. The solution is to add

-encoding UTF-8 -docencoding utf-8 -charset utf-8

into command line arguments!

UPDATE: more information about compilation Javadoc in Intellij IDEA see in my post

Tomcat 8 is not able to handle get request with '|' in query parameters?

The parameter tomcat.util.http.parser.HttpParser.requestTargetAllow is deprecated since Tomcat 8.5: tomcat official doc.

You can use relaxedQueryChars / relaxedPathChars in the connectors definition to allow these chars: tomcat official doc.

What does "request for member '*******' in something not a structure or union" mean?

It may also happen in the following case:

eg. if we consider the push function of a stack:

typedef struct stack
    int a[20];
    int head;

void push(stack **s)
    int data;
    printf("Enter data:");
    scanf("%d",&(*s->a[++*s->head])); /* this is where the error is*/

    stack *s;
    s=(stack *)calloc(1,sizeof(stack));
    return 0;

The error is in the push function and in the commented line. The pointer s has to be included within the parentheses. The correct code:

scanf("%d",&( (*s)->a[++(*s)->head]));

Format numbers to strings in Python

str() in python on an integer will not print any decimal places.

If you have a float that you want to ignore the decimal part, then you can use str(int(floatValue)).

Perhaps the following code will demonstrate:

>>> str(5)
>>> int(8.7)

java: use StringBuilder to insert at the beginning

This thread is quite old, but you could also think about a recursive solution passing the StringBuilder to fill. This allows to prevent any reverse processing etc. Just need to design your iteration with a recursion and carefully decide for an exit condition.

public class Test {

    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder();
        doRecursive(sb, 100, 0);

    public static void doRecursive(StringBuilder sb, int limit, int index) {
        if (index < limit) {
            doRecursive(sb, limit, index + 1);

How to find out mySQL server ip address from phpmyadmin

The SQL query SHOW VARIABLES WHERE Variable_name = 'hostname' will show you the hostname of the MySQL server which you can easily resolve to its IP address.

SHOW VARIABLES WHERE Variable_name = 'port' Will give you the port number.

You can find details about this in MySQL's manual: SHOW VARIABLES Syntax and 5.1.4. Server System Variables

A weighted version of random.choice

If your list of weighted choices is relatively static, and you want frequent sampling, you can do one O(N) preprocessing step, and then do the selection in O(1), using the functions in this related answer.

# run only when `choices` changes.
preprocessed_data = prep(weight for _,weight in choices)

# O(1) selection
value = choices[sample(preprocessed_data)][0]

How to draw a dotted line with css?

Using HTML:

<div class="horizontal_dotted_line"></div>

and in styles.css:

  border-bottom: 1px dotted [color];
  width: [put your width here]px;

The source was not found, but some or all event logs could not be searched. Inaccessible logs: Security

See creating a registry key.

This problem can occur not only due to permissions, but also due to event source key missing because it wasn't registered successfully (you need admin privileges to do it - if you just open Visual Studio as usual and run the program normally it won't be enough). Make sure that your event source "MyApp" is actually registered, i.e. that it appears in the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\Application.

From MSDN EventLog.CreateEventSource():

To create an event source in Windows Vista and later or Windows Server 2003, you must have administrative privileges.

So you must either run the event source registration code as an admin (also, check if the source already exists before - see the above MSDN example) or you can manually add the key to the registry:

  1. create a regkey HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\Application\MyApp;
  2. inside, create a string value EventMessageFile and set its value to e.g. C:\Windows\Microsoft.NET\Framework\v2.0.50727\EventLogMessages.dll

MYSQL query between two timestamps

You just need to convert your dates to UNIX_TIMESTAMP. You can write your query like this:

FROM eventList
  date BETWEEN
      UNIX_TIMESTAMP('2013/03/27 23:59:59');

When you don't specify the time, MySQL will assume 00:00:00 as the time for the given date.

How to get full width in body element

You can use CSS to do it for example


Detect user scroll down or scroll up in jQuery

To differentiate between scroll up/down in jQuery, you could use:

var mousewheelevt = (/Firefox/i.test(navigator.userAgent)) ? "DOMMouseScroll" : "mousewheel" //FF doesn't recognize mousewheel as of FF3.x
$('#yourDiv').bind(mousewheelevt, function(e){

    var evt = window.event || e //equalize event object     
    evt = evt.originalEvent ? evt.originalEvent : evt; //convert to originalEvent if possible               
    var delta = evt.detail ? evt.detail*(-40) : evt.wheelDelta //check for detail first, because it is used by Opera and FF

    if(delta > 0) {
        //scroll up
        //scroll down

This method also works in divs that have overflow:hidden.

I successfully tested it in FireFox, IE and Chrome.

Exception in thread "main" java.lang.Error: Unresolved compilation problems

Two possibilities here. Java Version incompatible or import

ReactJS map through Object

When calling Object.keys it returns a array of the object's keys.

Object.keys({ test: '', test2: ''}) // ['test', 'test2']

When you call Array#map the function you pass will give you 2 arguments;

  1. the item in the array,
  2. the index of the item.

When you want to get the data, you need to use item (or in the example below keyName) instead of i

{Object.keys(subjects).map((keyName, i) => (
    <li className="travelcompany-input" key={i}>
        <span className="input-label">key: {i} Name: {subjects[keyName]}</span>

<div> cannot appear as a descendant of <p>

Your component might be rendered inside another component (such as a <Typography> ... </Typography>). Therefore, it will load your component inside a <p> .. </p> which is not allowed.

Fix: Remove <Typography>...</Typography> because this is only used for plain text inside a <p>...</p> or any other text element such as headings.

How do I write a RGB color value in JavaScript?

this is better function

function RGB2HTML(red, green, blue)
    var decColor =0x1000000+ blue + 0x100 * green + 0x10000 *red ;
    return '#'+decColor.toString(16).substr(1);

How to add multiple classes to a ReactJS Component?

This is how you can do that with ES6:

className = {`
      ${itemId === activeItemId ? 'active' : ''}
      ${anotherProperty === true ? 'class1' : 'class2'}

You can list multiple classes and conditions and also you can include static classes. It is not necessary to add an additional library.

Good luck ;)

Stored Procedure parameter default value - is this a constant or a variable

It has to be a constant - the value has to be computable at the time that the procedure is created, and that one computation has to provide the value that will always be used.

Look at the definition of sys.all_parameters:

default_value sql_variant If has_default_value is 1, the value of this column is the value of the default for the parameter; otherwise, NULL.

That is, whatever the default for a parameter is, it has to fit in that column.

As Alex K pointed out in the comments, you can just do:

CREATE PROCEDURE [dbo].[problemParam] 
    @StartDate INT = NULL,
    @EndDate INT = NULL
   SET @StartDate = COALESCE(@StartDate,CONVERT(INT,(CONVERT(CHAR(8),GETDATE()-130,112))))

provided that NULL isn't intended to be a valid value for @StartDate.

As to the blog post you linked to in the comments - that's talking about a very specific context - that, the result of evaluating GETDATE() within the context of a single query is often considered to be constant. I don't know of many people (unlike the blog author) who would consider a separate expression inside a UDF to be part of the same query as the query that calls the UDF.

Javascript Click on Element by Class

I'd suggest:


The above code assumes that the given element has both of those classes; otherwise, if the space is meant to imply an ancestor-descendant relationship:

document.querySelector('.rateRecipe .btns-one-small').click();

The method getElementsByClassName() takes a single class-name (rather than document.querySelector()/document.querySelectorAll(), which take a CSS selector), and you passed two (presumably class-names) to the method.


jquery to loop through table rows and cells, where checkob is checked, concatenate


I've updated your demo:

Also, I've changed two ^= to *=. See

And note the :checked selector. See

function createcodes() {

    //run through each row
    $('.authors-list tr').each(function (i, row) {

        // reference all the stuff you need first
        var $row = $(row),
            $family = $row.find('input[name*="family"]'),
            $grade = $row.find('input[name*="grade"]'),
            $checkedBoxes = $row.find('input:checked');

        $checkedBoxes.each(function (i, checkbox) {
            // assuming you layout the elements this way, 
            // we'll take advantage of .next()
            var $checkbox = $(checkbox),
                $line = $,
                $size = $;

                $family.val() + ' ' + $size.val() + ', ' + $grade.val()



Initializing a static std::map<int, int> in C++

Just wanted to share a pure C++ 98 work around:

#include <map>

std::map<std::string, std::string> aka;

struct akaInit
        aka[ "George" ] = "John";
        aka[ "Joe" ] = "Al";
        aka[ "Phil" ] = "Sue";
        aka[ "Smitty" ] = "Yando";
} AkaInit;

Jenkins pipeline how to change to another folder

The dir wrapper can wrap, any other step, and it all works inside a steps block, for example:

steps {
    sh "pwd"
    dir('your-sub-directory') {
      sh "pwd"
    sh "pwd"

Finding all cycles in a directed graph

There are two steps (algorithms) involved in finding all cycles in a DAG.

The first step is to use Tarjan's algorithm to find the set of strongly connected components.

  1. Start from any arbitrary vertex.
  2. DFS from that vertex. For each node x, keep two numbers, dfs_index[x] and dfs_lowval[x]. dfs_index[x] stores when that node is visited, while dfs_lowval[x] = min(dfs_low[k]) where k is all the children of x that is not the directly parent of x in the dfs-spanning tree.
  3. All nodes with the same dfs_lowval[x] are in the same strongly connected component.

The second step is to find cycles (paths) within the connected components. My suggestion is to use a modified version of Hierholzer's algorithm.

The idea is:

  1. Choose any starting vertex v, and follow a trail of edges from that vertex until you return to v. It is not possible to get stuck at any vertex other than v, because the even degree of all vertices ensures that, when the trail enters another vertex w there must be an unused edge leaving w. The tour formed in this way is a closed tour, but may not cover all the vertices and edges of the initial graph.
  2. As long as there exists a vertex v that belongs to the current tour but that has adjacent edges not part of the tour, start another trail from v, following unused edges until you return to v, and join the tour formed in this way to the previous tour.

Here is the link to a Java implementation with a test case:

SQL Server: UPDATE a table by using ORDER BY

The row_number() function would be the best approach to this problem.

    SET T.Number = R.rowNum
    FROM Test T
    JOIN (
        SELECT,row_number() over (order by T2.Id desc) rowNum from Test T2
    ) R on 

PHP date add 5 year to current date

To add one year to todays date use the following:

$oneYearOn = date('Y-m-d',strtotime(date("Y-m-d", mktime()) . " + 365 day"));

C# : changing listbox row color?

I find solution that instead of using ListBox I used ListView.It allows to change list items BackColor.

private void listView1_Refresh()
    for (int i = 0; i < listView1.Items.Count; i++)
        listView1.Items[i].BackColor = Color.Red;
        for (int j = 0; j < existingStudents.Count; j++)
            if (listView1.Items[i].ToString().Contains(existingStudents[j]))
                listView1.Items[i].BackColor = Color.Green;

Update value of a nested dictionary of varying depth

This question is old, but I landed here when searching for a "deep merge" solution. The answers above inspired what follows. I ended up writing my own because there were bugs in all the versions I tested. The critical point missed was, at some arbitrary depth of the two input dicts, for some key, k, the decision tree when d[k] or u[k] is not a dict was faulty.

Also, this solution does not require recursion, which is more symmetric with how dict.update() works, and returns None.

import collections
def deep_merge(d, u):
   """Do a deep merge of one dict into another.

   This will update d with values in u, but will not delete keys in d
   not found in u at some arbitrary depth of d. That is, u is deeply
   merged into d.

   Args -
     d, u: dicts

   Note: this is destructive to d, but not u.

   Returns: None
   stack = [(d,u)]
   while stack:
      d,u = stack.pop(0)
      for k,v in u.items():
         if not isinstance(v, collections.Mapping):
            # u[k] is not a dict, nothing to merge, so just set it,
            # regardless if d[k] *was* a dict
            d[k] = v

            # note: u[k] is a dict
            if k not in d:
                # add new key into d
                d[k] = v
            elif not isinstance(d[k], collections.Mapping):
                # d[k] is not a dict, so just set it to u[k],
                # overriding whatever it was
                d[k] = v
                # both d[k] and u[k] are dicts, push them on the stack
                # to merge
                stack.append((d[k], v))

How do I turn off the mysql password validation?

You can configure this in mysql configuration file open /etc/my.cnf file In this file all the lines which is configuring the password policy make those commented like


Uncomment and change the value of the properties you want to change.

List comprehension on a nested list?

This Problem can be solved without using for loop.Single line code will be sufficient for this. Using Nested Map with lambda function will also works here.

l = [['40', '20', '10', '30'], ['20', '20', '20', '20', '20', '30', '20'], ['30', '20', '30', '50', '10', '30', '20', '20', '20'], ['100', '100'], ['100', '100', '100', '100', '100'], ['100', '100', '100', '100']]

map(lambda x:map(lambda y:float(y),x),l)

And Output List would be as follows:

[[40.0, 20.0, 10.0, 30.0], [20.0, 20.0, 20.0, 20.0, 20.0, 30.0, 20.0], [30.0, 20.0, 30.0, 50.0, 10.0, 30.0, 20.0, 20.0, 20.0], [100.0, 100.0], [100.0, 100.0, 100.0, 100.0, 100.0], [100.0, 100.0, 100.0, 100.0]]

Removing black dots from li and ul

There you go, this is what I used to fix your problem:


nav ul { list-style-type: none; }


<li><a href="#">Milk</a>
   <li><a href="#">Goat</a></li>
   <li><a href="#">Cow</a></li>
<li><a href="#">Eggs</a>
   <li><a href="#">Free-range</a></li>
   <li><a href="#">Other</a></li>
<li><a href="#">Cheese</a>
   <li><a href="#">Smelly</a></li>
   <li><a href="#">Extra smelly</a></li>

Converting from longitude\latitude to Cartesian coordinates

The proj.4 software provides a command line program that can do the conversion, e.g.

echo $LON $LAT | cs2cs +proj=latlong +datum=WGS84 +to +proj=geocent +datum=WGS84

It also provides a C API. In particular, the function pj_geodetic_to_geocentric will do the conversion without having to set up a projection object first.

How to set a transparent background of JPanel?

(Feature Panel).setOpaque(false);

Hope this helps.

How can I list all tags for a Docker image on a remote registry?

Here's a Powershell script I wrote for Windows. Handles v1 and v2 repos:


param (
  [Parameter (Mandatory=$true)]$ImageName,
  [Parameter (Mandatory=$false)]$RegistryURL

if (!$RegistryURL) 
  $RegistryURL = ""

$list = ""
if ($RegistryURL -like "*v2*") 
  $list = "/list"

$URL = "$RegistryURL/$ImageName/tags$list"

write-debug $URL
$resp = Invoke-WebRequest -UseBasicParsing $URL | ConvertFrom-Json

if ($RegistryURL -like "*v2*") 
  $tags = $resp | select tags
} else {
  $tags = $resp | select name

Check synchronously if file/directory exists in Node.js

Another Update

Needing an answer to this question myself I looked up the node docs, seems you should not be using fs.exists, instead use and use outputted error to detect if a file does not exist:

from the docs:

fs.exists() is an anachronism and exists only for historical reasons. There should almost never be a reason to use it in your own code.

In particular, checking if a file exists before opening it is an anti-pattern that leaves you vulnerable to race conditions: another process may remove the file between the calls to fs.exists() and Just open the file and handle the error when it's not there.

Running stages in parallel with Jenkins workflow / pipeline

that syntax is now deprecated, you will get this error:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
WorkflowScript: 14: Expected a stage @ line 14, column 9.
       parallel firstTask: {

WorkflowScript: 14: Stage does not have a name @ line 14, column 9.
       parallel secondTask: {

2 errors

You should do something like:

stage("Parallel") {
    steps {
        parallel (
            "firstTask" : {
                //do some stuff
            "secondTask" : {
                // Do some other stuff in parallel

Just to add the use of node here, to distribute jobs across multiple build servers/ VMs:

pipeline {
  stages {
    stage("Work 1"){
      parallel ( "Build common Library":   
                  /// your stuff

        "Build Utilities" : {
               /// your stuff

All VMs should be labelled as to use as a pool.

Create an empty data.frame

If you are looking for shortness :


so you don't need to specify the column names separately. You get the default column type logical until you fill the data frame.

Error: Cannot find module '../lib/utils/unsupported.js' while using Ionic

Tried all above/older brew installation answers, none is working for my laptop.

Only below method could fix my issue.

1) Run following commands:

sudo rm -rf /usr/local/lib/node_modules/npm
brew uninstall --force node      

2) Then, proceed to Node.js Official Website to download latest package for new installation.

3) Run your npm command again, which should longer have any errors.

This method is working on macOS Mojave Version 10.14.4.

Enable IIS7 gzip


You can enable GZIP compression entirely in your Web.config file. This is particularly useful if you're on shared hosting and can't configure IIS directly, or you want your config to carry between all environments you target.

  <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files">
    <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll"/>
      <add mimeType="text/*" enabled="true"/>
      <add mimeType="message/*" enabled="true"/>
      <add mimeType="application/javascript" enabled="true"/>
      <add mimeType="*/*" enabled="false"/>
      <add mimeType="text/*" enabled="true"/>
      <add mimeType="message/*" enabled="true"/>
      <add mimeType="application/javascript" enabled="true"/>
      <add mimeType="*/*" enabled="false"/>
  <urlCompression doStaticCompression="true" doDynamicCompression="true"/>


To test whether compression is working or not, use the developer tools in Chrome or Firebug for Firefox and ensure the HTTP response header is set:

Content-Encoding: gzip

Note that this header won't be present if the response code is 304 (Not Modified). If that's the case, do a full refresh (hold shift or control while you press the refresh button) and check again.

Java format yyyy-MM-dd'T'HH:mm:ss.SSSz to yyyy-mm-dd HH:mm:ss

If you really gotta be fast (not that I believe you do):

char[] chars = sourceDate.toCharArray();
chars[10] = ' ';
String targetDate = new String(chars, 0, 19);

Wait .5 seconds before continuing code

Imports VB = Microsoft.VisualBasic

Public Sub wait(ByVal seconds As Single)
    Static start As Single
    start = VB.Timer()
    Do While VB.Timer() < start + seconds
End Sub

%20+ high cpu usage + no lag

Private Sub wait(ByVal seconds As Integer)
    For i As Integer = 0 To seconds * 100
End Sub

%0.1 cpu usage + high lag

How to avoid variable substitution in Oracle SQL Developer with 'trinidad & tobago'

Call this before the query:

set define off;

Alternatively, hacky:

update t set country = 'Trinidad and Tobago' where country = 'trinidad &' || ' tobago';

From Tuning SQL*Plus:

SET DEFINE OFF disables the parsing of commands to replace substitution variables with their values.

How to add image for button in android?

As he stated, used the ImageButton widget. Copy your image file within the Res/drawable/ directory of your project. While in XML simply go into the graphic representation (for simplicity) of your XML file and click on your ImageButton widget that you added, go to its properties sheet and click on the [...] in the src: field. Simply navigate to your image file. Also, make sure you're using a proper format; I tend to stick with .png files for my own reasons, but they work.

How to get the index of a maximum element in a NumPy array along one axis

argmax() will only return the first occurrence for each row.

If you ever need to do this for a shaped array, this works better than unravel:

import numpy as np
a = np.array([[1,2,3], [4,3,1]])  # Can be of any shape
indices = np.where(a == a.max())

You can also change your conditions:

indices = np.where(a >= 1.5)

The above gives you results in the form that you asked for. Alternatively, you can convert to a list of x,y coordinates by:

x_y_coords =  zip(indices[0], indices[1])

Why doesn't adding CORS headers to an OPTIONS route allow browsers to access my API?

Try this in your main js file:

app.use((req, res, next) => {
res.header("Access-Control-Allow-Origin", "*");
  "Authorization, X-API-KEY, Origin, X-Requested-With, Content-Type, Accept, Access-Control-Allow-Request-Method"
res.header("Access-Control-Allow-Methods", "GET, POST, OPTIONS, PUT, DELETE");
res.header("Allow", "GET, POST, OPTIONS, PUT, DELETE");

This should solve your problem

Examples of good gotos in C or C++

The classic need for GOTO in C is as follows

for ...
  for ...
      goto final;


There is no straightforward way to break out of nested loops without a goto.

LINQ Where with AND OR condition

from item in db.vw_Dropship_OrderItems
    where (listStatus != null ? listStatus.Contains(item.StatusCode) : true) &&
    (listMerchants != null ? listMerchants.Contains(item.MerchantId) : true)
    select item;

Might give strange behavior if both listMerchants and listStatus are both null.

Function to calculate distance between two coordinates

Try this. It is in and you need to convert it to Javascript. This function accepts parameters in decimal minutes.

    Private Function calculateDistance(ByVal long1 As String, ByVal lat1 As String, ByVal long2 As String, ByVal lat2 As String) As Double
    long1 = Double.Parse(long1)
    lat1 = Double.Parse(lat1)
    long2 = Double.Parse(long2)
    lat2 = Double.Parse(lat2)

    'conversion to radian
    lat1 = (lat1 * 2.0 * Math.PI) / 60.0 / 360.0
    long1 = (long1 * 2.0 * Math.PI) / 60.0 / 360.0
    lat2 = (lat2 * 2.0 * Math.PI) / 60.0 / 360.0
    long2 = (long2 * 2.0 * Math.PI) / 60.0 / 360.0

    ' use to different earth axis length
    Dim a As Double = 6378137.0        ' Earth Major Axis (WGS84)
    Dim b As Double = 6356752.3142     ' Minor Axis
    Dim f As Double = (a - b) / a        ' "Flattening"
    Dim e As Double = 2.0 * f - f * f      ' "Eccentricity"

    Dim beta As Double = (a / Math.Sqrt(1.0 - e * Math.Sin(lat1) * Math.Sin(lat1)))
    Dim cos As Double = Math.Cos(lat1)
    Dim x As Double = beta * cos * Math.Cos(long1)
    Dim y As Double = beta * cos * Math.Sin(long1)
    Dim z As Double = beta * (1 - e) * Math.Sin(lat1)

    beta = (a / Math.Sqrt(1.0 - e * Math.Sin(lat2) * Math.Sin(lat2)))
    cos = Math.Cos(lat2)
    x -= (beta * cos * Math.Cos(long2))
    y -= (beta * cos * Math.Sin(long2))
    z -= (beta * (1 - e) * Math.Sin(lat2))

    Return Math.Sqrt((x * x) + (y * y) + (z * z))
End Function

Edit The converted function in javascript

function calculateDistance(lat1, long1, lat2, long2)

      lat1 = (lat1 * 2.0 * Math.PI) / 60.0 / 360.0;      
      long1 = (long1 * 2.0 * Math.PI) / 60.0 / 360.0;    
      lat2 = (lat2 * 2.0 * Math.PI) / 60.0 / 360.0;   
      long2 = (long2 * 2.0 * Math.PI) / 60.0 / 360.0;       

      // use to different earth axis length    
      var a = 6378137.0;        // Earth Major Axis (WGS84)    
      var b = 6356752.3142;     // Minor Axis    
      var f = (a-b) / a;        // "Flattening"    
      var e = 2.0*f - f*f;      // "Eccentricity"      

      var beta = (a / Math.sqrt( 1.0 - e * Math.sin( lat1 ) * Math.sin( lat1 )));    
      var cos = Math.cos( lat1 );    
      var x = beta * cos * Math.cos( long1 );    
      var y = beta * cos * Math.sin( long1 );    
      var z = beta * ( 1 - e ) * Math.sin( lat1 );      

      beta = ( a / Math.sqrt( 1.0 -  e * Math.sin( lat2 ) * Math.sin( lat2 )));    
      cos = Math.cos( lat2 );   
      x -= (beta * cos * Math.cos( long2 ));    
      y -= (beta * cos * Math.sin( long2 ));    
      z -= (beta * (1 - e) * Math.sin( lat2 ));       

      return (Math.sqrt( (x*x) + (y*y) + (z*z) )/1000);  

How can I check if a user is logged-in in php?

else if (isset($_GET['actie']) && $_GET['actie']== "aanmelden"){

    $username= $_POST['username'];
    $password= md5($_POST['password']);
    $query = "SELECT password FROM tbl WHERE username = '$username'";
    $result= mysql_query($query);
    $row= mysql_fetch_array($result);

    if($password == $row['password']){
            $_SESSION['logged in'] = true;
            echo "Logged in";


How to ignore deprecation warnings in Python

Try the below code if you're Using Python3:

import sys

if not sys.warnoptions:
    import warnings

or try this...

import warnings

def fxn():
    warnings.warn("deprecated", DeprecationWarning)

with warnings.catch_warnings():

or try this...

import warnings

How do I get monitor resolution in Python?

For later versions of PyGtk:

import gi
gi.require_version("Gdk", "3.0")
from gi.repository import Gdk

display = Gdk.Display.get_default()
n_monitors = display.get_n_monitors()
print("there are %d monitors" % n_monitors)
for m in range(n_monitors):
  monitor = display.get_monitor(m)
  geometry = monitor.get_geometry()
  print("monitor %d: %d x %d" % (m, geometry.width, geometry.height))

AWS CLI S3 A client error (403) occurred when calling the HeadObject operation: Forbidden

When it comes to cross-account S3 access

An IAM user policy will not over-ride the policy defined for the bucket in the foreign account.

s3:GetObject must be allowed for accountA/user as well as on the accountB/bucket

IIS Manager in Windows 10

  • Run appwiz.cpl - brings up Programs and Features
  • Choose "Turn Windows Features On/Off"
  • Select the IIS Services you need

Fatal error: Cannot use object of type stdClass as array in

Sorry.Though it is a bit late but hope it would help others as well . Always use the stdClass object.e.g

 $getvidids = $ci->db->query("SELECT * FROM videogroupids WHERE videogroupid='$videogroup'   AND used='0' LIMIT 10");

foreach($getvidids->result() as $key=>$myids)

  $vidid[$key] = $myids->videoid;  // better methodology to retrieve and store multiple records in arrays in loop

What’s the difference between "Array()" and "[]" while declaring a JavaScript array?

Using the Array constructor makes a new array of the desired length and populates each of the indices with undefined, the assigned an array to a variable one creates the indices that you give it info for.

Illegal Character when trying to compile java code

  1. If using an IDE, specify the java file encoding (via the properties panel)
  2. If NOT using an IDE, use an advanced text-editor (I can recommend Notepad++) and set the encoding to "UTF without BOM", or "ANSI", if that suits you.

What is the parameter "next" used for in Express?

Next is used to pass control to the next middleware function. If not the request will be left hanging or open.

assign headers based on existing row in dataframe in R

The key here is to unlist the row first.

colnames(DF) <- as.character(unlist(DF[1,]))
DF = DF[-1, ]

How to [recursively] Zip a directory in PHP?

Try this link <-- MORE SOURCE CODE HERE

/** Include the Pear Library for Zip */
include ('Archive/Zip.php');

/** Create a Zipping Object...
* Name of zip file to be created..
* You can specify the path too */
$obj = new Archive_Zip('');
* create a file array of Files to be Added in Zip
$files = array('black.gif',

* creating zip file..if success do something else do something...
* if Error in file creation is either due to permission problem (Solution: give 777 to that folder)
* Or Corruption of File Problem..

if ($obj->create($files)) {
// echo 'Created successfully!';
} else {
//echo 'Error in file creation';

?>; // We'll be outputting a ZIP
header('Content-type: application/zip');

// It will be called
header('Content-Disposition: attachment; filename=""');

//read a file and send

Xamarin 2.0 vs Appcelerator Titanium vs PhoneGap

I haven't worked much with Appcelerator Titanium, but I'll put my understanding of it at the end.

I can speak a bit more to the differences between PhoneGap and Xamarin, as I work with these two 5 (or more) days a week.

If you are already familiar with C# and JavaScript, then the question I guess is, does the business logic lie in an area more suited to JavaScript or C#?


PhoneGap is designed to allow you to write your applications using JavaScript and HTML, and much of the functionality that they do provide is designed to mimic the current proposed specifications for the functionality that will eventually be available with HTML5. The big benefit of PhoneGap in my opinion is that since you are doing the UI with HTML, it can easily be ported between platforms. The downside is, because you are porting the same UI between platforms, it won't feel quite as at home in any of them. Meaning that, without further tweaking, you can't have an application that feels fully at home in iOS and Android, meaning that it has the iOS and Android styling. The majority of your logic can be written using JavaScript, which means it too can be ported between platforms. If the current PhoneGap API does most of what you want, then it's pretty easy to get up and running. If however, there are things you need from the device that are not in the API, then you get into the fun of Plugin Development, which will be in the native device's development language of choice (with one caveat, but I'll get to that), which means you would likely need to get up to speed quickly in Objective-C, Java, etc. The good thing about this model, is you can usually adapt many different native libraries to serve your purpose, and many libraries already have PhoneGap Plugins. Although you might not have much experience with these languages, there will at least be a plethora of examples to work from.


Xamarin.iOS and Xamarin.Android (also known as MonoTouch and MonoDroid), are designed to allow you to have one library of business logic, and use this within your application, and hook it into your UI. Because it's based on .NET 4.5, you get some awesome lambda notations, LINQ, and a whole bunch of other C# awesomeness, which can make writing your business logic less painful. The downside here is that Xamarin expects that you want to make your applications truly feel native on the device, which means that you will likely end up rewriting your UI for each platform, before hooking it together with the business logic. I have heard about MvvmCross, which is designed to make this easier for you, but I haven't really had an opportunity to look into it yet. If you are familiar with the MVVM system in C#, you may want to have a look at this. When it comes to native libraries, MonoTouch becomes interesting. MonoTouch requires a Binding library to tell your C# code how to link into the underlying Objective-C and Java code. Some of these libraries will already have bindings, but if yours doesn't, creating one can be, interesting. Xamarin has made a tool called Objective Sharpie to help with this process, and for the most part, it will get you 95% of the way there. The remaining 5% will probably take 80% of your time attempting to bind a library.


As noted in the comments below, Xamarin has released Xamarin Forms which is a cross platform abstraction around the platform specific UI components. Definitely worth the look.

PhoneGap / Xamarin Hybrid

Now because I said I would get to it, the caveat mentioned in PhoneGap above, is a Hybrid approach, where you can use PhoneGap for part, and Xamarin for part. I have quite a bit of experience with this, and I would caution you against it. Highly. The problem with this, is it is such a no mans' land that if you ever run into issues, almost no one will have come close to what you're doing, and will question what you're trying to do greatly. It is doable, but it's definitely not fun.

Appcelerator Titanium

As I mentioned before, I haven't worked much with Appcelerator Titanium, So for the differences between them, I will suggest you look at Comparing Titanium and Phonegap or Comparison between Corona, Phonegap, Titanium as it has a very thorough description of the differences. Basically, it appears that though they both use JavaScript, how that JavaScript is interpreted is slightly different. With Titanium, you will be writing your JavaScript to the Titanium SDK, whereas with PhoneGap, you will write your application using the PhoneGap API. As PhoneGap is very HTML5 and JavaScript standards compliant, you can use pretty much any JavaScript libraries you want, such as JQuery. With PhoneGap your user interface will be composed of HTML and CSS. With Titanium, you will benefit from their Cross-platform XML which appears to generate Native components. This means it will definitely have a better native look and feel.

How to fix JSP compiler warning: one JAR was scanned for TLDs yet contained no TLDs?

Uncomment this line (in /conf/

org.apache.jasper.compiler.TldLocationsCache.level = FINE

Work's for me in tomcat 7.0.53!

check output from CalledProcessError

If you want to get stdout and stderr back (including extracting it from the CalledProcessError in the event that one occurs), use the following:

import subprocess

command = ["ls", "-l"]
    output = subprocess.check_output(command, stderr=subprocess.STDOUT).decode()
    success = True 
except subprocess.CalledProcessError as e:
    output = e.output.decode()
    success = False


This is Python 2 and 3 compatible.

If your command is a string rather than an array, prefix this with:

import shlex
command = shlex.split(command)

How to prevent SIGPIPEs (or handle them properly)

Another method is to change the socket so it never generates SIGPIPE on write(). This is more convenient in libraries, where you might not want a global signal handler for SIGPIPE.

On most BSD-based (MacOS, FreeBSD...) systems, (assuming you are using C/C++), you can do this with:

int set = 1;
setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&set, sizeof(int));

With this in effect, instead of the SIGPIPE signal being generated, EPIPE will be returned.

Changing variable names with Python for loops

You could access your class's __dict__ attribute:

for i in range(3)
     self.__dict__['group%d' % i]=self.getGroup(selected, header+i)

But why can't you just use an array named group?

How to set up Automapper in ASP.NET Core

In my Startup.cs (Core 2.2, Automapper 8.1.1)

services.AddAutoMapper(new Type[] { typeof(DAL.MapperProfile) });            

In my data access project

namespace DAL
    public class MapperProfile : Profile
        // place holder for AddAutoMapper (to bring in the DAL assembly)

In my model definition

namespace DAL.Models
    public class PositionProfile : Profile
        public PositionProfile()
            CreateMap<Position, PositionDto_v1>();

    public class Position

Float a div right, without impacting on design

What do you mean by impacts? Content will flow around a float. That's how they work.

If you want it to appear above your design, try setting:

z-index: 10;  
position: absolute;  
right: 0;  
top: 0;

Refresh page after form submitting

You want a form that self submits? Then you just leave the "action" parameter blank.


<form method="post" action="" />

If you want to process the form with this page, then make sure that you have some mechanism in the form or session data to test whether it was properly submitted and to ensure you're not trying to process the empty form.

You might want another mechanism to decide if the form was filled out and submitted but is invalid. I usually use a hidden input field that matches a session variable to decide whether the user has clicked submit or just loaded the page for the first time. By giving a unique value each time and setting the session data to the same value, you can also avoid duplicate submissions if the user clicks submit twice.

How to show uncommitted changes in Git and some Git diffs in detail

For me, the only thing which worked is

git diff HEAD

including the staged files, git diff --cached only shows staged files.

Conditional replacement of values in a data.frame

Since you are conditionally indexing df$est, you also need to conditionally index the replacement vector df$a:

index <- df$b == 0
df$est[index] <- (df$a[index] - 5)/2.533 

Of course, the variable index is just temporary, and I use it to make the code a bit more readible. You can write it in one step:

df$est[df$b == 0] <- (df$a[df$b == 0] - 5)/2.533 

For even better readibility, you can use within:

df <- within(df, est[b==0] <- (a[b==0]-5)/2.533)

The results, regardless of which method you choose:

          a b      est
1  11.77000 2 0.000000
2  10.90000 3 0.000000
3  10.32000 2 0.000000
4  10.96000 0 2.352941
5   9.90600 0 1.936834
6  10.70000 0 2.250296
7  11.43000 1 0.000000
8  11.41000 2 0.000000
9  10.48512 4 0.000000
10 11.19000 0 2.443743

As others have pointed out, an alternative solution in your example is to use ifelse.

Is it possible to use the SELECT INTO clause with UNION [ALL]?

For MS Access queries, this worked:

SELECT * INTO tmpFerdeen FROM( 
    SELECT top(100) *
    FROM Customers 
    SELECT top(100) *  
    FROM CustomerEurope 
    SELECT top(100) *  
    FROM CustomerAsia 
    SELECT top(100) *  
    FROM CustomerAmericas

This did NOT work in MS Access

SELECT top(100) * 
  INTO tmpFerdeen
  FROM Customers
  SELECT top(100) * 
  FROM CustomerEurope
  SELECT top(100) * 
  FROM CustomerAsia
  SELECT top(100) * 
  FROM CustomerAmericas

Meaning of "referencing" and "dereferencing" in C

For a start, you have them backwards: & is reference and * is dereference.

Referencing a variable means accessing the memory address of the variable:

int i = 5;
int * p;
p = &i; //&i returns the memory address of the variable i.

Dereferencing a variable means accessing the variable stored at a memory address:

int i = 5;
int * p;
p = &i;
*p = 7; //*p returns the variable stored at the memory address stored in p, which is i.
//i is now 7

Print a div content using Jquery

If you want to do this without an extra plugin (like printThis), I think this should work. The idea is to have a special div that will be printed, while everything else is hidden using CSS. This is easier to do if the div is a direct child of the body tag, so you will have to move whatever you want to print to a div like that. S So begin with creating a div with id print-me as a direct child to your body tag. Then use this code to print the div:

$("#btn").click(function () {
    //Copy the element you want to print to the print-me div.
    //Apply some styles to hide everything else while printing.
    //Print the window.
    //Restore the styles.
    //Clear up the div.

The styles you need are these:

@media print {
    /* Hide everything in the body when printing... */
    body.printing * { display: none; }
    /* ...except our special div. */
    body.printing #print-me { display: block; }

@media screen {
    /* Hide the special layer from the screen. */
    #print-me { display: none; }

The reason why we should only apply the @print styles when the printing class is present is that the page should be printed as normally if the user prints the page by selecting File -> Print.

PHP convert string to hex and hex to string

function hexToStr($hex){
    // Remove spaces if the hex string has spaces
    $hex = str_replace(' ', '', $hex);
    return hex2bin($hex);
// Test it 
$hex    = "53 44 43 30 30 32 30 30 30 31 37 33";
echo hexToStr($hex); // SDC002000173

 * Test Hex To string with PHP UNIT
 * @param  string $value
 * @return 
public function testHexToString()
    $string = 'SDC002000173';
    $hex    = "53 44 43 30 30 32 30 30 30 31 37 33";
    $result = hexToStr($hex);


How to target only IE (any version) within a stylesheet?

Internet Explorer 9 and lower : You could use conditional comments to load an IE-specific stylesheet for any version (or combination of versions) that you wanted to specifically below using external stylesheet.

<!--[if IE]>
  <link rel="stylesheet" type="text/css" href="all-ie-only.css" />

However, beginning in version 10, conditional comments are no longer supported in IE.

Internet Explorer 10 & 11 : Create a media query using -ms-high-contrast, in which you place your IE 10 and 11-specific CSS styles. Because -ms-high-contrast is Microsoft-specific (and only available in IE 10+), it will only be parsed in Internet Explorer 10 and greater.

@media all and (-ms-high-contrast: none), (-ms-high-contrast: active) {
     /* IE10+ CSS styles go here */

Microsoft Edge 12 : Can use the @supports rule Here is a link with all the info about this rule

@supports (-ms-accelerator:true) {
  /* IE Edge 12+ CSS styles go here */ 

Inline rule IE8 detection

I have 1 more option but it is only detect IE8 and below version.

  /* For IE css hack */
  margin-top: 10px\9 /* apply to all ie from 8 and below */
  *margin-top:10px;  /* apply to ie 7 and below */
  _margin-top:10px; /* apply to ie 6 and below */

As you specefied for embeded stylesheet. I think you need to use media query and condition comment for below version.

Press any key to continue

Here is what I use.

Write-Host -NoNewLine 'Press any key to continue...';
$null = $Host.UI.RawUI.ReadKey('NoEcho,IncludeKeyDown');

Is it a good practice to use try-except-else in Python?

"I do not know if it is out of ignorance, but I do not like that kind of programming, as it is using exceptions to perform flow control."

In the Python world, using exceptions for flow control is common and normal.

Even the Python core developers use exceptions for flow-control and that style is heavily baked into the language (i.e. the iterator protocol uses StopIteration to signal loop termination).

In addition, the try-except-style is used to prevent the race-conditions inherent in some of the "look-before-you-leap" constructs. For example, testing os.path.exists results in information that may be out-of-date by the time you use it. Likewise, Queue.full returns information that may be stale. The try-except-else style will produce more reliable code in these cases.

"It my understanding that exceptions are not errors, they should only be used for exceptional conditions"

In some other languages, that rule reflects their cultural norms as reflected in their libraries. The "rule" is also based in-part on performance considerations for those languages.

The Python cultural norm is somewhat different. In many cases, you must use exceptions for control-flow. Also, the use of exceptions in Python does not slow the surrounding code and calling code as it does in some compiled languages (i.e. CPython already implements code for exception checking at every step, regardless of whether you actually use exceptions or not).

In other words, your understanding that "exceptions are for the exceptional" is a rule that makes sense in some other languages, but not for Python.

"However, if it is included in the language itself, there must be a good reason for it, isn't it?"

Besides helping to avoid race-conditions, exceptions are also very useful for pulling error-handling outside loops. This is a necessary optimization in interpreted languages which do not tend to have automatic loop invariant code motion.

Also, exceptions can simplify code quite a bit in common situations where the ability to handle an issue is far removed from where the issue arose. For example, it is common to have top level user-interface code calling code for business logic which in turn calls low-level routines. Situations arising in the low-level routines (such as duplicate records for unique keys in database accesses) can only be handled in top-level code (such as asking the user for a new key that doesn't conflict with existing keys). The use of exceptions for this kind of control-flow allows the mid-level routines to completely ignore the issue and be nicely decoupled from that aspect of flow-control.

There is a nice blog post on the indispensibility of exceptions here.

Also, see this Stack Overflow answer: Are exceptions really for exceptional errors?

"What is the reason for the try-except-else to exist?"

The else-clause itself is interesting. It runs when there is no exception but before the finally-clause. That is its primary purpose.

Without the else-clause, the only option to run additional code before finalization would be the clumsy practice of adding the code to the try-clause. That is clumsy because it risks raising exceptions in code that wasn't intended to be protected by the try-block.

The use-case of running additional unprotected code prior to finalization doesn't arise very often. So, don't expect to see many examples in published code. It is somewhat rare.

Another use-case for the else-clause is to perform actions that must occur when no exception occurs and that do not occur when exceptions are handled. For example:

recip = float('Inf')
    recip = 1 / f(x)
except ZeroDivisionError:'Infinite result')
else:'Finite result')

Another example occurs in unittest runners:

    tests_run += 1
except Exception:
    tests_failed += 1
    logging.exception('Failing test case: %r', case)
    print('F', end='')
else:'Successful test case: %r', case)
    print('.', end='')

Lastly, the most common use of an else-clause in a try-block is for a bit of beautification (aligning the exceptional outcomes and non-exceptional outcomes at the same level of indentation). This use is always optional and isn't strictly necessary.

How to split large text file in windows?

You can use the command split for this task. For example this command entered into the command prompt

split YourLogFile.txt -b 500m

creates several files with a size of 500 MByte each. This will take several minutes for a file of your size. You can rename the output files (by default called "xaa", "xab",... and so on) to *.txt to open it in the editor of your choice.

Make sure to check the help file for the command. You can also split the log file by number of lines or change the name of your output files.

(tested on Windows 7 64 bit)

Image re-size to 50% of original size in HTML

You can use the x descriptor of the srcset attribute as such:

<!-- Original image -->
<img src="" />

<!-- With a 80% size reduction (1/0.8=1.25) -->
<img srcset=" 1.25x" />

<!-- With a 50% size reduction (1/0.5=2) -->
<img srcset=" 2x" />

Currently supported by all browsers except IE. (caniuse)

MDN documentation

Android Studio AVD - Emulator: Process finished with exit code 1

These are known errors from libGL and libstdc++

You can quick fix this by change to use Software for Emulated Performance Graphics option, in the AVD settings.

Or try to use the (which is available in your system) instead of the one bundled inside Android SDK. There are 2 ways to replace it:

  • The emulator has a switch -use-system-libs. You can found it here: ~/Android/Sdk/tools/emulator -avd Nexus_5_API_23 -use-system-libs.

    This option force Linux emulator to load the system libstdc++ (but not Qt libraries), in cases where the bundled ones (from Android SDK) prevent it from loading or working correctly. See this commit

  • Alternatively you can set the ANDROID_EMULATOR_USE_SYSTEM_LIBS environment variable to 1 for your user/system.

    This has the benefit of making sure that the emulator will work even if you launched it from within Android Studio.

See: libGL error and libstdc++: Cannot launch AVD in emulator - Issue Tracker

Named colors in matplotlib

I constantly forget the names of the colors I want to use and keep coming back to this question =)

The previous answers are great, but I find it a bit difficult to get an overview of the available colors from the posted image. I prefer the colors to be grouped with similar colors, so I slightly tweaked the matplotlib answer that was mentioned in a comment above to get a color list sorted in columns. The order is not identical to how I would sort by eye, but I think it gives a good overview.

I updated the image and code to reflect that 'rebeccapurple' has been added and the three sage colors have been moved under the 'xkcd:' prefix since I posted this answer originally.

enter image description here

I really didn't change much from the matplotlib example, but here is the code for completeness.

import matplotlib.pyplot as plt
from matplotlib import colors as mcolors

colors = dict(mcolors.BASE_COLORS, **mcolors.CSS4_COLORS)

# Sort colors by hue, saturation, value and name.
by_hsv = sorted((tuple(mcolors.rgb_to_hsv(mcolors.to_rgba(color)[:3])), name)
                for name, color in colors.items())
sorted_names = [name for hsv, name in by_hsv]

n = len(sorted_names)
ncols = 4
nrows = n // ncols

fig, ax = plt.subplots(figsize=(12, 10))

# Get height and width
X, Y = fig.get_dpi() * fig.get_size_inches()
h = Y / (nrows + 1)
w = X / ncols

for i, name in enumerate(sorted_names):
    row = i % nrows
    col = i // nrows
    y = Y - (row * h) - h

    xi_line = w * (col + 0.05)
    xf_line = w * (col + 0.25)
    xi_text = w * (col + 0.3)

    ax.text(xi_text, y, name, fontsize=(h * 0.8),

    ax.hlines(y + h * 0.1, xi_line, xf_line,
              color=colors[name], linewidth=(h * 0.8))

ax.set_xlim(0, X)
ax.set_ylim(0, Y)

fig.subplots_adjust(left=0, right=1,
                    top=1, bottom=0,
                    hspace=0, wspace=0)

Additional named colors

Updated 2017-10-25. I merged my previous updates into this section.


If you would like to use additional named colors when plotting with matplotlib, you can use the xkcd crowdsourced color names, via the 'xkcd:' prefix:

plt.plot([1,2], lw=4, c='xkcd:baby poop green')

Now you have access to a plethora of named colors!

enter image description here


The default Tableau colors are available in matplotlib via the 'tab:' prefix:

plt.plot([1,2], lw=4, c='tab:green')

There are ten distinct colors:

enter image description here


You can also plot colors by their HTML hex code:

plt.plot([1,2], lw=4, c='#8f9805')

This is more similar to specifying and RGB tuple rather than a named color (apart from the fact that the hex code is passed as a string), and I will not include an image of the 16 million colors you can choose from...

For more details, please refer to the matplotlib colors documentation and the source file specifying the available colors,

Undefined reference to main - collect2: ld returned 1 exit status

I my case I found out the void for the main function declaration was missing.

I was previously using Visual Studio in Windows and this was never a problem, so I thought I might leave it out now too.

How to edit data in result grid in SQL Server Management Studio

First of all right click the tale select 'Edit All Rows', select 'Query Designer -> Pane -> SQL ', after that you can edit the query output in the grid.

How to resolve 'npm should be run outside of the node repl, in your normal shell'

It's better to use the actual (msi) installer from instead of downloading the node executable only. The installer includes npm and makes it easier to manage your node installation. There is an installer for both 32-bit and 64-bit Windows.

Also a couple of other tidbits:

  • Installing modules globally doesn't do what you might expect. The only modules you should install globally (the -g flag in npm) are ones that install commands. So to install Express you would just do npm install express and that will install Express to your current working directory. If you were instead looking for the Express project generator (command), you need to do npm install -g express-generator for Express 4.

  • You can use node anywhere from your command prompt to execute scripts. For example if you have already written a separate script: node foo.js. Or you can open up the REPL (as you've already found out) by just selecting the node.js (start menu) shortcut or by just typing node in a command prompt.

Listen for key press in .NET console app

with below code you can listen SpaceBar pressing , in middle of your console execution and pause until another key is pressed and also listen for EscapeKey for breaking the main loop

static ConsoleKeyInfo cki = new ConsoleKeyInfo();

while(true) {
      if (WaitOrBreak()) break;
      //your main code

 private static bool WaitOrBreak(){
        if (Console.KeyAvailable) cki = Console.ReadKey(true);
        if (cki.Key == ConsoleKey.Spacebar)
            while (Console.KeyAvailable == false)
            cki = new ConsoleKeyInfo();
        if (cki.Key == ConsoleKey.Escape) return true;
        return false;

JavaScript backslash (\) in variables is causing an error

You may want to try the following, which is more or less the standard way to escape user input:

function stringEscape(s) {
    return s ? s.replace(/\\/g,'\\\\').replace(/\n/g,'\\n').replace(/\t/g,'\\t').replace(/\v/g,'\\v').replace(/'/g,"\\'").replace(/"/g,'\\"').replace(/[\x00-\x1F\x80-\x9F]/g,hex) : s;
    function hex(c) { var v = '0'+c.charCodeAt(0).toString(16); return '\\x'+v.substr(v.length-2); }

This replaces all backslashes with an escaped backslash, and then proceeds to escape other non-printable characters to their escaped form. It also escapes single and double quotes, so you can use the output as a string constructor even in eval (which is a bad idea by itself, considering that you are using user input). But in any case, it should do the job you want.

Python: IndexError: list index out of range

As the error notes, the problem is in the line:

if guess[i] == winning_numbers[i]

The error is that your list indices are out of range--that is, you are trying to refer to some index that doesn't even exist. Without debugging your code fully, I would check the line where you are adding guesses based on input:

for i in range(tickets):
    bubble = input("What numbers do you want to choose for ticket #"+str(i+1)+"?\n").split(" ")

The size of how many guesses you are giving your user is based on

# Prompts the user to enter the number of tickets they wish to play.
tickets = int(input("How many lottery tickets do you want?\n"))

So if the number of tickets they want is less than 5, then your code here

for i in range(5):

if guess[i] == winning_numbers[i]:
    match = match+1

return match

will throw an error because there simply aren't that many elements in the guess list.

Printing 1 to 1000 without loop or conditionals

Trigger a fatal error! Here's the file, countup.c:

#include <stdio.h>
#define MAX 1000
int boom;
int foo(n) {
    boom = 1 / (MAX-n+1);
    printf("%d\n", n);
int main() {

Compile, then execute on a shell prompt:

$ ./countup
Floating point exception

This does indeed print the numbers from 1 to 1000, without any loops or conditionals!

SQL conditional SELECT

@selectField1 AS bit
@selectField2 AS bit

    WHEN @selectField1 THEN Field1
    WHEN @selectField2 THEN Field2
    ELSE someDefaultField
FROM Table

Is this what you're looking for?

Insert data to MySql DB and display if insertion is success or failure

According to the book PHP and MySQL for Dynamic Web Sites (4th edition)


$r = mysqli_query($dbc, $q);

For simple queries like INSERT, UPDATE, DELETE, etc. (which do not return records), the $r variable—short for result—will be either TRUE or FALSE, depending upon whether the query executed successfully.

Keep in mind that “executed successfully” means that it ran without error; it doesn’t mean that the query’s execution necessarily had the desired result; you’ll need to test for that.

Then how to test?

While the mysqli_num_rows() function will return the number of rows generated by a SELECT query, mysqli_affected_rows() returns the number of rows affected by an INSERT, UPDATE, or DELETE query. It’s used like so:

$num = mysqli_affected_rows($dbc);

Unlike mysqli_num_rows(), the one argument the function takes is the database connection ($dbc), not the results of the previous query ($r).

Remove by _id in MongoDB console


How to install Flask on Windows?

heres a step by step procedure (assuming you've already installed python):

  1. first install chocolatey:

open terminal (Run as Administrator) and type in the command line:

C:/> @powershell -NoProfile -ExecutionPolicy Bypass -Command "iex ((new-object net.webclient).DownloadString(''))" && SET PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin

it will take some time to get chocolatey installed on your machine. sit back n relax...

  1. now install pip. type in terminal cinst easy.install pip

  2. now type in terminal: pip install flask

YOU'RE DONE !!! Tested on Win 8.1 with Python 2.7

Error CS1705: "which has a higher version than referenced assembly"

In my scenario, I edited the .csproj file for my dotnetCore app. I noticed that the TargetFramework tag had a value of netcoreapp2.1 and the RuntimeFrameworkVersion tag a value of 2.0.0. So I changed the RuntimeFrameworkVersion to 2.1.0, saved, restarted VS and rebuilt and then it resolved the errors.

Hope this will help you ...

Good Luck,


DataColumn Name from DataRow (not DataTable)

use DataTable object instead:

 private void doMore(DataTable dt)
    foreach(DataColumn dc in dt.Columns)

How to include clean target in Makefile?

In makefile language $@ means "name of the target", so rm -f $@ translates to rm -f clean.

You need to specify to rm what exactly you want to delete, like rm -f *.o code1 code2

What does "while True" mean in Python?

While most of these answers are correct to varying degrees, none of them are as succinct as I would like.

Put simply, using while True: is just a way of running a loop that will continue to run until you explicitly break out of it using break or return. Since True will always evaluate to True, you have to force the loop to end when you want it to.

while True:
    # do stuff

    if some_condition:

    # do more stuff - code here WILL NOT execute when `if some_condition:` evaluates to True

While normally a loop would be set to run until the while condition is false, or it reaches a predefined end point:

do_next = True

while do_next:

    # do stuff

    if some_condition:
        do_next = False

    # do more stuff - code here WILL execute even when `if some_condition:` evaluates to True

Those two code chunks effectively do the same thing

If the condition your loop evaluates against is possibly a value not directly in your control, such as a user input value, then validating the data and explicitly breaking out of the loop is usually necessary, so you'd want to do it with either method.

The while True format is more pythonic since you know that break is breaking the loop at that exact point, whereas do_next = False could do more stuff before the next evaluation of do_next.

Android Canvas.drawText

Worked this out, turns out that is not the same as Color.BLACK. Changed the code to:

Paint paint = new Paint(); 

canvas.drawText("Some Text", 10, 25, paint); 

and it all works fine now!!

How do you append an int to a string in C++?

Well, if you use cout you can just write the integer directly to it, as in

std::cout << text << i;

The C++ way of converting all kinds of objects to strings is through string streams. If you don't have one handy, just create one.

#include <sstream>

std::ostringstream oss;
oss << text << i;
std::cout << oss.str();

Alternatively, you can just convert the integer and append it to the string.

oss << i;
text += oss.str();

Finally, the Boost libraries provide boost::lexical_cast, which wraps around the stringstream conversion with a syntax like the built-in type casts.

#include <boost/lexical_cast.hpp>

text += boost::lexical_cast<std::string>(i);

This also works the other way around, i.e. to parse strings.

Maven: Failed to retrieve plugin descriptor error

In my case, even my system is not behind proxy, I got same issue. I was able to resolve by typing mvn help:archetype before mvn archetype:generate

Can I hide/show asp:Menu items based on role?

Try this:

protected void Menu1_DataBound(object sender, EventArgs e)

private void recursiveMenuVisit(MenuItemCollection items)
            MenuItem[] itemsToRemove = new MenuItem[items.Count];
            int i = 0;

            foreach (MenuItem item in items)
                if (item.NavigateUrl.Contains("Contact.aspx"))
                    itemsToRemove[i] = item;
                    if (item.ChildItems.Count > 0) recursiveMenuVisit(item.ChildItems);

            for(int j=0; j < i; j++)

How to set "value" to input web element using selenium?

driver.findElement("invoice_supplier_id")).setAttribute("value", "your value");

Including jars in classpath on commandline (javac or apt)

Use the -cp or -classpath switch.

$ java -help  
Usage: java [-options] class [args...]  
           (to execute a class)  
   or  java [-options] -jar jarfile [args...]  
           (to execute a jar file)  

where options include:  
    -cp <class search path of directories and zip/jar files>  
    -classpath <class search path of directories and zip/jar files>  
                  A ; separated list of directories, JAR archives,  
                  and ZIP archives to search for class files.  

(Note that the separator used to separate entries on the classpath differs between OSes, on my Windows machine it is ;, in *nix it is usually :.)

unary operator expected in shell script when comparing null value with string

Why all people want to use '==' instead of simple '=' ? It is bad habit! It used only in [[ ]] expression. And in (( )) too. But you may use just = too! It work well in any case. If you use numbers, not strings use not parcing to strings and then compare like strings but compare numbers. like that

let -i i=5 # garantee that i is nubmber
test $i -eq 5 && echo "$i is equal 5" || echo "$i not equal 5"

It's match better and quicker. I'm expert in C/C++, Java, JavaScript. But if I use bash i never use '==' instead '='. Why you do so?

Cast received object to a List<object> or IEnumerable<object>

You need to type cast using as operator like this.

private void MyMethod(object myObject)  
if(myObject is IEnumerable)  
    List<object> collection = myObject as(List<object>); 
    ... do something   
    ... do something  

CSS :selected pseudo class similar to :checked, but for <select> elements

Actually you can only style few CSS properties on :modified option elements. color does not work, background-color either, but you can set a background-image.

You can couple this with gradients to do the trick.

option:checked {_x000D_
  background: linear-gradient(#5A2569, #5A2569);_x000D_

Works on gecko/webkit.

mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead


/* Database config */

$db_host        = 'localhost';
$db_user        = '~';
$db_pass        = '~';
$db_database    = 'banners'; 

/* End config */

$mysqli = new mysqli($db_host, $db_user, $db_pass, $db_database);
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());


How to convert Varchar to Double in sql?

This might be more desirable, that is use float instead

SELECT fullName, CAST(totalBal as float) totalBal FROM client_info ORDER BY totalBal DESC

How can I loop through all rows of a table? (MySQL)

Mr Purple's example I used in mysql trigger like that,

Select COUNT(*) from user where deleted_at is null INTO n;
SET i=0;
  INSERT INTO user_notification(notification_id,status,userId)values(new.notification_id,1,(Select userId FROM user LIMIT i,1)) ;
  SET i = i + 1;

Timestamp Difference In Hours for PostgreSQL

postgresql get seconds difference between timestamps

    (extract (epoch from (
        '2012-01-01 18:25:00'::timestamp - '2012-01-01 18:25:02'::timestamp

which prints:


Because the timestamps are two seconds apart. Take the number and divide by 60 to get minutes, divide by 60 again to get hours.

What does principal end of an association means in 1:1 relationship in Entity framework

You can also use the [Required] data annotation attribute to solve this:

public class Foo
    public string FooId { get; set; }

    public Boo Boo { get; set; }

public class Boo
    public string BooId { get; set; }

    public Foo Foo {get; set; }

Foo is required for Boo.

Basic authentication for REST API using spring restTemplate

Use setBasicAuth to define credentials

HttpHeaders headers = new HttpHeaders();
headers.setBasicAuth("myUsername", myPassword);

Then create the request like you prefer.


HttpEntity<String> request = new HttpEntity<String>(headers);
ResponseEntity<String> response =, HttpMethod.GET, 
request, String.class);
String body = response.getBody();

What is default color for text in textview?

hey you can try this

ColorStateList colorStateList = textView.getTextColors();
String hexColor = String.format("#%06X", (0xFFFFFF & colorStateList.getDefaultColor()));

How to read text files with ANSI encoding and non-English letters?

using (StreamWriter writer = new StreamWriter(File.Open(@"E:\Sample.txt", FileMode.Append), Encoding.GetEncoding(1250)))  ////File.Create(path)
            writer.Write("Sample Text");