What are the uses of MySQL's IS and IS NOT operators?-Mysql Tutorial-php.cn

What are the uses of MySQL's IS and IS NOT operators?

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Release： 2023-08-23 22:17:04

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MySQL的IS和IS NOT运算符有什么用途？

In MySQL, the IS and IS NOT operators are both used to test a value against a Boolean value.

The syntax of the IS operator can be as follows:

Val IS Boolean_val

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Here Val is the value that we want to test against Boolean value.

Boolean_val is the Boolean value against which the value would be tested and it can be TRUE, FALSE or UNKNOWN.

The syntax of IS NOT operator can be as follows −

Here, Val is the value we want to test against the boolean value.

Boolean_val is the Boolean value to be tested, it can be TRUE, FALSE or UNKNOWN.

IS NOT The syntax of the operator can be as follows −

Val IS NOT Boolean_val

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Here, Val is the boolean value we want to test against value.

Boolean_val is the Boolean value to be tested against, which can be TRUE, FALSE or UNKNOWN.

The following MySQL statements will demonstrate the above −

mysql> Select 1 IS TRUE, 0 IS FALSE, NULL IS UNKNOWN;
+-----------+------------+-----------------+
| 1 IS TRUE | 0 IS FALSE | NULL IS UNKNOWN |
+-----------+------------+-----------------+
|         1 |          1 |               1 |
+-----------+------------+-----------------+
1 row in set (0.00 sec)

mysql> Select 1 IS NOT TRUE, 0 IS NOT FALSE, NULL IS NOT UNKNOWN;
+---------------+----------------+---------------------+
| 1 IS NOT TRUE | 0 IS NOT FALSE | NULL IS NOT UNKNOWN |
+---------------+----------------+---------------------+
|             0 |              0 |                   0 |
+---------------+----------------+---------------------+
1 row in set (0.00 sec)

mysql> Select 0 IS NOT TRUE, 1 IS NOT FALSE, NULL IS NOT UNKNOWN;
+---------------+----------------+---------------------+
| 0 IS NOT TRUE | 1 IS NOT FALSE | NULL IS NOT UNKNOWN |
+---------------+----------------+---------------------+
|             1 |              1 |                   0 |
+---------------+----------------+---------------------+
1 row in set (0.00 sec)

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