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# 逻辑运算符

## 一元逻辑运算符

- 支持运算符：`!`
- 输入数据类型：`BOOLEAN`。
- 输出数据类型：`BOOLEAN`。
- 注意：`!`的优先级很高，记得使用括号调整优先级。

## 二元逻辑运算符

- 支持运算符 
  - AND:`and`,`&`, `&&`
  - OR:`or`,`|`,`||`

- 输入数据类型：`BOOLEAN`。

- 返回类型 `BOOLEAN`。

- 注意：当某个时间戳下左操作数和右操作数都为`BOOLEAN`类型时，二元逻辑操作才会有输出结果。

**示例：**

```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|
+-----------------------------+-----------+-----------+----------------+--------------------------+---------------------------+------------------------------------------------+
```