docs/UserGuide/Operators-Functions/Logical.md

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# Logical Operators

## Unary Logical Operators

Supported operator `!`

Supported input data types: `BOOLEAN`

Output data type: `BOOLEAN`

Hint: the priority of `!` is the same as `-`. Remember to use brackets to modify priority.

## Binary Logical Operators

Supported operators AND:`and`,`&`, `&&`; OR:`or`,`|`,`||`

Supported input data types: `BOOLEAN`

Output data type: `BOOLEAN`

Note: Only when the left operand and the right operand under a certain timestamp are both `BOOLEAN` type, the binary logic operation will have an output value.

**Example:**

```sql
select a, b, a > 10, a <= b, !(a <= b), a > 10 && a > b from root.test;
```

运行结果
```
IoTDB> select a, b, a > 10, a <= b, !(a <= b), a > 10 && a > b from root.test;
+-----------------------------+-----------+-----------+----------------+--------------------------+---------------------------+------------------------------------------------+
|                         Time|root.test.a|root.test.b|root.test.a > 10|root.test.a <= root.test.b|!root.test.a <= root.test.b|(root.test.a > 10) & (root.test.a > root.test.b)|
+-----------------------------+-----------+-----------+----------------+--------------------------+---------------------------+------------------------------------------------+
|1970-01-01T08:00:00.001+08:00|         23|       10.0|            true|                     false|                       true|                                            true|
|1970-01-01T08:00:00.002+08:00|         33|       21.0|            true|                     false|                       true|                                            true|
|1970-01-01T08:00:00.004+08:00|         13|       15.0|            true|                      true|                      false|                                           false|
|1970-01-01T08:00:00.005+08:00|         26|        0.0|            true|                     false|                       true|                                            true|
|1970-01-01T08:00:00.008+08:00|          1|       22.0|           false|                      true|                      false|                                           false|
|1970-01-01T08:00:00.010+08:00|         23|       12.0|            true|                     false|                       true|                                            true|
+-----------------------------+-----------+-----------+----------------+--------------------------+---------------------------+------------------------------------------------+
```