mysql group concat function sql example

mysql group concat function sql example - concatenating more than one rows value to a single string

Before running this example please make a database hr which can be found: click here to garb the script

mysql-group-concat-function-sql-example.php


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  <h2>mysql group concat function sql example - concatenating more than one rows value to a single string</h2>
  <pre>
   <?php
    /*
     ---------------------------------------------------------------------------------------------------
     we have a table named EMPLOYEES in the HR database and we would like to concat multiple rows value
     to a single column , that is we want all employees of IT department(DepartmentID=60) in a single
     string by concatenating FirstName and LastName columns using mysql group_concat() function
     ---------------------------------------------------------------------------------------------------
    */
    $sql = "
     SELECT  GROUP_CONCAT(FirstName, LastName)
     FROM  employees
     WHERE  DepartmentID=60
    ";
    /*
     ----------------------------------------------------------------------------------
     Here DepartmentID=60 means IT department.

     Note : GROUP_CONCAT() function also returns NULL if all of the given argument(s) is NULL.
     
     ALSO NOTE(my experience) ABOUT NULL:
     
     1. NULL IS A VALUE THAT IS UNAVAILABLE
     2. NULL IS A VALUE THAT IS UNASSIGNED
     3. NULL IS A VALUE THAT IS UNKNOWN
     4. NULL IS A VALUE THAT IS INAPPLICABLE
     5. NULL IS A VALUE THAT IS NOT EVEN EQUAL TO NULL
     6. NULL IS A VALUE THAT IS NOT EQUAL TO ZERO : ZERO IS A NUMBER
     7. NULL IS A VALUE THAT IS NOT EQUAL TO BLANK SPACE OR EMPTY STRING : SPACE IS A CHARACTER
     AND 8. COLUMNS OF ANY DATATYPE CAN CONTAIN NULL VALUE
     ----------------------------------------------------------------------------------
    */
    /*
     -------------------------------------------------------
     USING PHP YOU CAN DO THIS. 
     GET CONNECTION TO DATABASE BY USING : mysql_connect()
     SELECT DATABASE BY USING : mysql_select_db()
     THEN RUN THE QUERY
     -------------------------------------------------------
    */
    

    mysql_connect('localhost', 'root', 'root');
    mysql_select_db('hr');
    mysql_query($sql);
    
    /*
     ------------------------------------------------------------------------------
     TO RUN THE PHP CODE PROVIDE REAL DATA TO mysql_connect AND mysql_select_db()
     ------------------------------------------------------------------------------
    */
   ?>
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mysql group concat function sql example - concatenating more than one rows value to a single string - output in the client

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