mysql中的NULL的判斷

標籤：

mysql> delete from `zhangchao` where x=‘NULL‘;

Query OK, 0 rows affected (0.00 sec)mysql> delete from `zhangchao` where x=NULL; Query OK, 0 rows affected (0.00 sec)mysql> select * from zhangchao;+------+-------+| x    | y     |+------+-------+| xxx  | yyy   || NULL | NULL  || xxx  | james || xxx  | lucy  || xxx  | alex  |+------+-------+5 rows in set (0.00 sec)mysql> delete from `zhangchao` where x  is null;Query OK, 1 row affected (0.00 sec)mysql> select * from zhangchao;+------+-------+| x    | y     |+------+-------+| xxx  | yyy   || xxx  | james || xxx  | lucy  || xxx  | alex  |+------+-------+4 rows in set (0.00 sec)mysql>

需要使用is null來進行判斷。

mysql中的NULL的判斷