[php] MySQL, Concatenate two columns

There are two columns in a MySQL table: SUBJECT and YEAR.

I want to generate an alphanumeric unique number which holds the concatenated data from SUBJECT and YEAR.

How can I do this? Is it possible to use a simple operator like +?

In php, we have two option to concatenate table columns.

First Option using Query

In query, CONCAT keyword used to concatenate two columns

SELECT CONCAT(`SUBJECT`,'_', `YEAR`) AS subject_year FROM `table_name`;

Second Option using symbol ( . )

After fetch the data from database table, assign the values to variable, then using ( . ) Symbol and concatenate the values

$subject = $row['SUBJECT'];
$year = $row['YEAR'];
$subject_year = $subject . "_" . $year;

Instead of underscore( _ ) , we will use the spaces, comma, letters,numbers..etc

You can use php built in CONCAT() for this.

SELECT CONCAT(`name`, ' ', `email`) as password_email FROM `table`;

change filed name as your requirement

then the result is

and if you want to concat same filed using other field which same then

SELECT filed1 as category,filed2 as item, GROUP_CONCAT(CAST(filed2 as CHAR)) as item_name FROM `table` group by filed1 

then this is output

$crud->set_relation('id','students','{first_name} {last_name}');
$crud->display_as('student_id','Students Name');

You can use the CONCAT function like this:

SELECT CONCAT(`SUBJECT`, ' ', `YEAR`) FROM `table`

Update:

To get that result you can try this:

SET @rn := 0;

SELECT CONCAT(`SUBJECT`,'-',`YEAR`,'-',LPAD(@rn := @rn+1,3,'0'))
FROM `table`

In query, CONCAT_WS() function.

This function not only add multiple string values and makes them a single string value. It also let you define separator ( ” “, ” , “, ” – “,” _ “, etc.).

Syntax –

CONCAT_WS( SEPERATOR, column1, column2, ... )

Example

SELECT 
topic, 
CONCAT_WS( " ", subject, year ) AS subject_year 
FROM table