IS NOT

语法说明

IS NOT 运算符用于测试数值是否为布尔值，若不是布尔值，则返回结果为 true。其中 boolean_value 可以为 TRUE、FALSE 或 UNKNOWN。

语法结构

1. > IS NOT boolean_value

示例

1. mysql> SELECT 1 IS NOT TRUE, 0 IS NOT FALSE, NULL IS NOT UNKNOWN;
2. +-----------+------------+----------+
3. | 1 != true | 0 != false | null !=  |
4. +-----------+------------+----------+
5. | false     | false      | NULL     |
6. +-----------+------------+----------+
7. 1 row in set (0.01 sec)