I see that within MySQL there are Cast() and Convert() functions to create integers from values, but is there any way to check to see if a value is an integer? Something like is_int() in PHP is what I am looking for.
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This also works:
CAST( coulmn_value AS UNSIGNED ) // will return 0 if not numeric string.
for example
SELECT CAST('a123' AS UNSIGNED) // returns 0
SELECT CAST('123' AS UNSIGNED) // returns 123 i.e. > 0
Match it against a regular expression.
c.f. http://forums.mysql.com/read.php?60,1907,38488#msg-38488 as quoted below:
Re: IsNumeric() clause in MySQL??
Posted by: kevinclark ()
Date: August 08, 2005 01:01PM
I agree. Here is a function I created for MySQL 5:
CREATE FUNCTION IsNumeric (sIn varchar(1024)) RETURNS tinyint
RETURN sIn REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
This allows for an optional plus/minus sign at the beginning, one optional decimal point, and the rest numeric digits.
for me the only thing that works is:
CREATE FUNCTION IsNumeric (SIN VARCHAR(1024)) RETURNS TINYINT
RETURN SIN REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
from kevinclark all other return useless stuff for me in case of 234jk456 or 12 inches
Suppose we have column with alphanumeric field having entries like
a41q
1458
xwe8
1475
asde
9582
.
.
.
.
.
qe84
and you want highest numeric value from this db column (in this case it is 9582) then this query will help you
SELECT Max(column_name) from table_name where column_name REGEXP '^[0-9]+$'
for me the only thing that works is:
CREATE FUNCTION IsNumeric (SIN VARCHAR(1024)) RETURNS TINYINT
RETURN SIN REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
from kevinclark all other return useless stuff for me in case of 234jk456 or 12 inches
What about:
WHERE table.field = "0" or CAST(table.field as SIGNED) != 0
to test for numeric and the corrolary:
WHERE table.field != "0" and CAST(table.field as SIGNED) = 0
This also works:
CAST( coulmn_value AS UNSIGNED ) // will return 0 if not numeric string.
for example
SELECT CAST('a123' AS UNSIGNED) // returns 0
SELECT CAST('123' AS UNSIGNED) // returns 123 i.e. > 0
To check if a value is Int in Mysql, we can use the following query. This query will give the rows with Int values
SELECT col1 FROM table WHERE concat('',col * 1) = col;
Here is the simple solution for it assuming the data type is varchar
select * from calender where year > 0
It will return true if the year is numeric else false
Match it against a regular expression.
c.f. http://forums.mysql.com/read.php?60,1907,38488#msg-38488 as quoted below:
Re: IsNumeric() clause in MySQL??
Posted by: kevinclark ()
Date: August 08, 2005 01:01PM
I agree. Here is a function I created for MySQL 5:
CREATE FUNCTION IsNumeric (sIn varchar(1024)) RETURNS tinyint
RETURN sIn REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
This allows for an optional plus/minus sign at the beginning, one optional decimal point, and the rest numeric digits.
This works well for VARCHAR where it begins with a number or not..
WHERE concat('',fieldname * 1) != fieldname
may have restrictions when you get to the larger NNNNE+- numbers
The best i could think of a variable is a int Is a combination with MySQL's functions CAST() and LENGTH().
This method will work on strings, integers, doubles/floats datatypes.
SELECT (LENGTH(CAST(<data> AS UNSIGNED))) = (LENGTH(<data>)) AS is_int
see demo http://sqlfiddle.com/#!9/ff40cd/44
it will fail if the column has a single character value. if column has a value 'A' then Cast('A' as UNSIGNED) will evaluate to 0 and LENGTH(0) will be 1. so LENGTH(Cast('A' as UNSIGNED))=LENGTH(0) will evaluate to 1=1 => 1
True Waqas Malik totally fogotten to test that case. the patch is.
SELECT <data>, (LENGTH(CAST(<data> AS UNSIGNED))) = CASE WHEN CAST(<data> AS UNSIGNED) = 0 THEN CAST(<data> AS UNSIGNED) ELSE (LENGTH(<data>)) END AS is_int;
Results
**Query #1**
SELECT 1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1 AS UNSIGNED) = 0 THEN CAST(1 AS UNSIGNED) ELSE (LENGTH(1)) END AS is_int;
| 1 | is_int |
| --- | ------ |
| 1 | 1 |
---
**Query #2**
SELECT 1.1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1.1 AS UNSIGNED) = 0 THEN CAST(1.1 AS UNSIGNED) ELSE (LENGTH(1.1)) END AS is_int;
| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0 |
---
**Query #3**
SELECT "1", (LENGTH(CAST("1" AS UNSIGNED))) = CASE WHEN CAST("1" AS UNSIGNED) = 0 THEN CAST("1" AS UNSIGNED) ELSE (LENGTH("1")) END AS is_int;
| 1 | is_int |
| --- | ------ |
| 1 | 1 |
---
**Query #4**
SELECT "1.1", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1.1" AS UNSIGNED) = 0 THEN CAST("1.1" AS UNSIGNED) ELSE (LENGTH("1.1")) END AS is_int;
| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0 |
---
**Query #5**
SELECT "1a", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1a" AS UNSIGNED) = 0 THEN CAST("1a" AS UNSIGNED) ELSE (LENGTH("1a")) END AS is_int;
| 1a | is_int |
| --- | ------ |
| 1a | 0 |
---
**Query #6**
SELECT "1.1a", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("1.1a" AS UNSIGNED) = 0 THEN CAST("1.1a" AS UNSIGNED) ELSE (LENGTH("1.1a")) END AS is_int;
| 1.1a | is_int |
| ---- | ------ |
| 1.1a | 0 |
---
**Query #7**
SELECT "a1", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("a1" AS UNSIGNED) = 0 THEN CAST("a1" AS UNSIGNED) ELSE (LENGTH("a1")) END AS is_int;
| a1 | is_int |
| --- | ------ |
| a1 | 0 |
---
**Query #8**
SELECT "a1.1", (LENGTH(CAST("a1.1" AS UNSIGNED))) = CASE WHEN CAST("a1.1" AS UNSIGNED) = 0 THEN CAST("a1.1" AS UNSIGNED) ELSE (LENGTH("a1.1")) END AS is_int;
| a1.1 | is_int |
| ---- | ------ |
| a1.1 | 0 |
---
**Query #9**
SELECT "a", (LENGTH(CAST("a" AS UNSIGNED))) = CASE WHEN CAST("a" AS UNSIGNED) = 0 THEN CAST("a" AS UNSIGNED) ELSE (LENGTH("a")) END AS is_int;
| a | is_int |
| --- | ------ |
| a | 0 |
see demo
Suppose we have column with alphanumeric field having entries like
a41q
1458
xwe8
1475
asde
9582
.
.
.
.
.
qe84
and you want highest numeric value from this db column (in this case it is 9582) then this query will help you
SELECT Max(column_name) from table_name where column_name REGEXP '^[0-9]+$'
Match it against a regular expression.
c.f. http://forums.mysql.com/read.php?60,1907,38488#msg-38488 as quoted below:
Re: IsNumeric() clause in MySQL??
Posted by: kevinclark ()
Date: August 08, 2005 01:01PM
I agree. Here is a function I created for MySQL 5:
CREATE FUNCTION IsNumeric (sIn varchar(1024)) RETURNS tinyint
RETURN sIn REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
This allows for an optional plus/minus sign at the beginning, one optional decimal point, and the rest numeric digits.
This works well for VARCHAR where it begins with a number or not..
WHERE concat('',fieldname * 1) != fieldname
may have restrictions when you get to the larger NNNNE+- numbers
To check if a value is Int in Mysql, we can use the following query. This query will give the rows with Int values
SELECT col1 FROM table WHERE concat('',col * 1) = col;
I have tried using the regular expressions listed above, but they do not work for the following:
SELECT '12 INCHES' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...
The above will return 1 (TRUE), meaning the test of the string '12 INCHES' against the regular expression above, returns TRUE. It looks like a number based on the regular expression used above. In this case, because the 12 is at the beginning of the string, the regular expression interprets it as a number.
The following will return the right value (i.e. 0) because the string starts with characters instead of digits
SELECT 'TOP 10' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...
The above will return 0 (FALSE) because the beginning of the string is text and not numeric.
However, if you are dealing with strings that have a mix of numbers and letters that begin with a number, you will not get the results you want. REGEXP will interpret the string as a valid number when in fact it is not.
Here is the simple solution for it assuming the data type is varchar
select * from calender where year > 0
It will return true if the year is numeric else false
Match it against a regular expression.
c.f. http://forums.mysql.com/read.php?60,1907,38488#msg-38488 as quoted below:
Re: IsNumeric() clause in MySQL??
Posted by: kevinclark ()
Date: August 08, 2005 01:01PM
I agree. Here is a function I created for MySQL 5:
CREATE FUNCTION IsNumeric (sIn varchar(1024)) RETURNS tinyint
RETURN sIn REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$';
This allows for an optional plus/minus sign at the beginning, one optional decimal point, and the rest numeric digits.
What about:
WHERE table.field = "0" or CAST(table.field as SIGNED) != 0
to test for numeric and the corrolary:
WHERE table.field != "0" and CAST(table.field as SIGNED) = 0
I have tried using the regular expressions listed above, but they do not work for the following:
SELECT '12 INCHES' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...
The above will return 1 (TRUE), meaning the test of the string '12 INCHES' against the regular expression above, returns TRUE. It looks like a number based on the regular expression used above. In this case, because the 12 is at the beginning of the string, the regular expression interprets it as a number.
The following will return the right value (i.e. 0) because the string starts with characters instead of digits
SELECT 'TOP 10' REGEXP '^(-|\\+){0,1}([0-9]+\\.[0-9]*|[0-9]*\\.[0-9]+|[0-9]+)$' FROM ...
The above will return 0 (FALSE) because the beginning of the string is text and not numeric.
However, if you are dealing with strings that have a mix of numbers and letters that begin with a number, you will not get the results you want. REGEXP will interpret the string as a valid number when in fact it is not.
The best i could think of a variable is a int Is a combination with MySQL's functions CAST() and LENGTH().
This method will work on strings, integers, doubles/floats datatypes.
SELECT (LENGTH(CAST(<data> AS UNSIGNED))) = (LENGTH(<data>)) AS is_int
see demo http://sqlfiddle.com/#!9/ff40cd/44
it will fail if the column has a single character value. if column has a value 'A' then Cast('A' as UNSIGNED) will evaluate to 0 and LENGTH(0) will be 1. so LENGTH(Cast('A' as UNSIGNED))=LENGTH(0) will evaluate to 1=1 => 1
True Waqas Malik totally fogotten to test that case. the patch is.
SELECT <data>, (LENGTH(CAST(<data> AS UNSIGNED))) = CASE WHEN CAST(<data> AS UNSIGNED) = 0 THEN CAST(<data> AS UNSIGNED) ELSE (LENGTH(<data>)) END AS is_int;
Results
**Query #1**
SELECT 1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1 AS UNSIGNED) = 0 THEN CAST(1 AS UNSIGNED) ELSE (LENGTH(1)) END AS is_int;
| 1 | is_int |
| --- | ------ |
| 1 | 1 |
---
**Query #2**
SELECT 1.1, (LENGTH(CAST(1 AS UNSIGNED))) = CASE WHEN CAST(1.1 AS UNSIGNED) = 0 THEN CAST(1.1 AS UNSIGNED) ELSE (LENGTH(1.1)) END AS is_int;
| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0 |
---
**Query #3**
SELECT "1", (LENGTH(CAST("1" AS UNSIGNED))) = CASE WHEN CAST("1" AS UNSIGNED) = 0 THEN CAST("1" AS UNSIGNED) ELSE (LENGTH("1")) END AS is_int;
| 1 | is_int |
| --- | ------ |
| 1 | 1 |
---
**Query #4**
SELECT "1.1", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1.1" AS UNSIGNED) = 0 THEN CAST("1.1" AS UNSIGNED) ELSE (LENGTH("1.1")) END AS is_int;
| 1.1 | is_int |
| --- | ------ |
| 1.1 | 0 |
---
**Query #5**
SELECT "1a", (LENGTH(CAST("1.1" AS UNSIGNED))) = CASE WHEN CAST("1a" AS UNSIGNED) = 0 THEN CAST("1a" AS UNSIGNED) ELSE (LENGTH("1a")) END AS is_int;
| 1a | is_int |
| --- | ------ |
| 1a | 0 |
---
**Query #6**
SELECT "1.1a", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("1.1a" AS UNSIGNED) = 0 THEN CAST("1.1a" AS UNSIGNED) ELSE (LENGTH("1.1a")) END AS is_int;
| 1.1a | is_int |
| ---- | ------ |
| 1.1a | 0 |
---
**Query #7**
SELECT "a1", (LENGTH(CAST("1.1a" AS UNSIGNED))) = CASE WHEN CAST("a1" AS UNSIGNED) = 0 THEN CAST("a1" AS UNSIGNED) ELSE (LENGTH("a1")) END AS is_int;
| a1 | is_int |
| --- | ------ |
| a1 | 0 |
---
**Query #8**
SELECT "a1.1", (LENGTH(CAST("a1.1" AS UNSIGNED))) = CASE WHEN CAST("a1.1" AS UNSIGNED) = 0 THEN CAST("a1.1" AS UNSIGNED) ELSE (LENGTH("a1.1")) END AS is_int;
| a1.1 | is_int |
| ---- | ------ |
| a1.1 | 0 |
---
**Query #9**
SELECT "a", (LENGTH(CAST("a" AS UNSIGNED))) = CASE WHEN CAST("a" AS UNSIGNED) = 0 THEN CAST("a" AS UNSIGNED) ELSE (LENGTH("a")) END AS is_int;
| a | is_int |
| --- | ------ |
| a | 0 |
see demo
Source: Stackoverflow.com