IFNULL
The IFNULL() function return the first expression if it is not NULL. Otherwise, the second expression is returned.
Syntax
IFNULL( <expr1>, <expr2>)
Arguments
Arguments | Description |
---|---|
<expr1> | Any general expression of any data type. |
<expr2> | Any general expression that evaluates to the same data type as \<expr1>. |
Return Type
The data type of the returned value is the data type of \<expr1>.
Examples
SELECT a, b, IFNULL(a, b) FROM t;
+------+------+--------------+
| a | b | IFNULL(a, b) |
+------+------+--------------+
| 0 | 1 | 0 |
| 0 | NULL | 0 |
| NULL | 1 | 1 |
| NULL | NULL | NULL |
+------+------+--------------+