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逻辑操作符.md 15.50 KB

# 逻辑操作符<a name="ZH-CN_TOPIC_0242370429"></a>

常用的逻辑操作符有AND、OR和NOT，他们的运算结果有三个值，分别为TRUE、FALSE和NULL，其中NULL代表未知。他们运算优先级顺序为：NOT\>AND\>OR。

运算规则请参见[表1](#zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_table261968)，表中的a和b代表逻辑表达式。

**表 1**  运算规则表

<a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_table261968"></a>
<table><thead align="left"><tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row14174287"><th class="cellrowborder" valign="top" width="17.858214178582145%" id="mcps1.2.6.1.1"><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p15580856"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p15580856"></a>a
</th>
<th class="cellrowborder" valign="top" width="16.91830816918308%" id="mcps1.2.6.1.2"><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p11570636"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p11570636"></a>b
</th>
<th class="cellrowborder" valign="top" width="22.187781221877813%" id="mcps1.2.6.1.3"><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p53894476"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p53894476"></a>a <a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_b28106029"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_b28106029"></a>AND b的结果
</th>
<th class="cellrowborder" valign="top" width="24.047595240475953%" id="mcps1.2.6.1.4"><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p56705893"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p56705893"></a>a<a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_i26791430"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_i26791430"></a> <a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_b51228171"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_b51228171"></a>OR b的结果
</th>
<th class="cellrowborder" valign="top" width="18.988101189881014%" id="mcps1.2.6.1.5"><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p671108162345"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p671108162345"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a5f16416fb0014e5db6e88d3f9e0a0bdf"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a5f16416fb0014e5db6e88d3f9e0a0bdf"></a>NOT a的结果
</th>
</tr>
</thead>
<tbody><tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row35808814"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p63803972"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p63803972"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p12900098"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p12900098"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p24844601"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p24844601"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p64852782"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p64852782"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a8afb8ac1c16840f9aa53175db421414c"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a8afb8ac1c16840f9aa53175db421414c"></a>FALSE
</td>
</tr>
<tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row11193076"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p21665674"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p21665674"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p61636999"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p61636999"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p42824655"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p42824655"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p61070791"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p61070791"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_ae8646e7d4ff44b708c577f0c5a1e68cb"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_ae8646e7d4ff44b708c577f0c5a1e68cb"></a>FALSE
</td>
</tr>
<tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row34418071"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p8195406"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p8195406"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p44074598"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p44074598"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p59440254"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p59440254"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p4884189"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p4884189"></a>TRUE
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a652a1aa5a32e4dcf897629c160222703"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a652a1aa5a32e4dcf897629c160222703"></a>FALSE
</td>
</tr>
<tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row43573962"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p63694367"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p63694367"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p23143541"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p23143541"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p48685036"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p48685036"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p59584160"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p59584160"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a9d89f7ed8c13412e8c66633341826620"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a9d89f7ed8c13412e8c66633341826620"></a>TRUE
</td>
</tr>
<tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row13720756"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p18452325"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p18452325"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p23390658"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p23390658"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p29014962"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p29014962"></a>FALSE
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p48768158"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p48768158"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a7af404da2fa74b5294e52f6572a2f0a9"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a7af404da2fa74b5294e52f6572a2f0a9"></a>TRUE
</td>
</tr>
<tr id="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_row28321591"><td class="cellrowborder" valign="top" width="17.858214178582145%" headers="mcps1.2.6.1.1 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p16697147"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p16697147"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="16.91830816918308%" headers="mcps1.2.6.1.2 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p34610504"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p34610504"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="22.187781221877813%" headers="mcps1.2.6.1.3 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p38558574"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p38558574"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="24.047595240475953%" headers="mcps1.2.6.1.4 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p57704564"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_zh-cn_topic_0058966260_p57704564"></a>NULL
</td>
<td class="cellrowborder" valign="top" width="18.988101189881014%" headers="mcps1.2.6.1.5 "><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a4c963086817f4d7c864b735cfb81c8d0"></a><a name="zh-cn_topic_0237121965_zh-cn_topic_0059778733_a4c963086817f4d7c864b735cfb81c8d0"></a>NULL
</td>
</tr>
</tbody>
</table>

>![](public_sys-resources/icon-note.gif) **说明：**   
>操作符AND和OR具有交换性，即交换左右两个操作数，不影响其结果。

一键复制编辑原始数据按行查看历史

提交于 2020-05-29 19:27 . Upload openGauss information

逻辑操作符

常用的逻辑操作符有AND、OR和NOT，他们的运算结果有三个值，分别为TRUE、FALSE和NULL，其中NULL代表未知。他们运算优先级顺序为：NOT>AND>OR。

运算规则请参见表1，表中的a和b代表逻辑表达式。

表 1 运算规则表

a	b	a AND b的结果	a OR b的结果	NOT a的结果
TRUE	TRUE	TRUE	TRUE	FALSE
TRUE	FALSE	FALSE	TRUE	FALSE
TRUE	NULL	NULL	TRUE	FALSE
FALSE	FALSE	FALSE	FALSE	TRUE
FALSE	NULL	FALSE	NULL	TRUE
NULL	NULL	NULL	NULL	NULL

说明：
操作符AND和OR具有交换性，即交换左右两个操作数，不影响其结果。

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