MySQL IFNULL 사용

 

IFNULL(expr1,expr2)

 

 

If expr1 is not NULL, IFNULL() returns expr1; otherwise it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used.

mysql> SELECT IFNULL(1,0);
        -> 1
mysql> SELECT IFNULL(NULL,10);
        -> 10
mysql> SELECT IFNULL(1/0,10);
        -> 10
mysql> SELECT IFNULL(1/0,'yes');
        -> 'yes'

 

mysql> CREATE TABLE tmp SELECT IFNULL(1,'test') AS test;
mysql> DESCRIBE tmp;
+-------+---------+------+-----+---------+-------+
| Field  | Type      | Null   | Key  | Default   | Extra  |
+-------+---------+------+-----+---------+-------+
| test    | char(4)  |         |        |              |          |
+-------+---------+------+-----+---------+-------+