The IFNULL() function returns a value based on whether a specified expression evaluates to NULL. : IFNULL « Function « SQL / MySQL






  1. SQL / MySQL
  2. Function
  3. IFNULL

The IFNULL() function returns a value based on whether a specified expression evaluates to NULL.

     
mysql>
IFNULL(<expression1>, <expression2>)
mysql>
The function returns <expression1> if it is not NULL;
otherwise, it returns <expression2>.
mysql>
mysql> SELECT IFNULL(10*NULL, 'expression incorrect');
+-----------------------------------------+
| IFNULL(10*NULL, 'expression incorrect') |
+-----------------------------------------+
| expression incorrect                    |
+-----------------------------------------+
1 row in set (0.00 sec)

mysql>








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5.SELECT ISNULL(NULL), ISNULL(0), ISNULL(1);
6.The following expression returns expr2 if expr1 is NULL, and expr1 otherwise: