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IS NULL

Description

The IS NOT NULL function tests whether a value is NULL.

It returns TRUE if a NULL value is found, otherwise it returns FALSE. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.

Syntax

> expression IS NULL

Examples

> SELECT 1 IS NULL, 0 IS NULL, NULL IS NULL;
+-----------+-----------+--------------+
| 1 is null | 0 is null | null is null |
+-----------+-----------+--------------+
| false     | false     | true         |
+-----------+-----------+--------------+
1 row in set (0.01 sec)
> create table t1 (a boolean,b bool);
> insert into t1 values (0,1),(true,false),(true,1),(0,false),(NULL,NULL);
> select * from t1;
+-------+-------+
| a     | b     |
+-------+-------+
| false | true  |
| true  | false |
| true  | true  |
| false | false |
| NULL  | NULL  |
+-------+-------+
> select * from t1 where a IS NULL;
+------+------+
| a    | b    |
+------+------+
| NULL | NULL |
+------+------+
1 row in set (0.01 sec)