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end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">快速上手</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">基础概念</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">部署与运维</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable active" type="button"><!----><span class="vp-sidebar-title">使用手册</span><span class="vp-arrow down"></span></button><ul class="vp-sidebar-links"><li><!--[--><a aria-label="语法约定" class="vp-link nav-link active vp-sidebar-link vp-sidebar-page active nav-link active vp-sidebar-link vp-sidebar-page active" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html"><!---->语法约定<!----></a><ul class="vp-sidebar-sub-headers"><li class="vp-sidebar-sub-header"><a aria-label="字面值常量" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#字面值常量"><!---->字面值常量<!----></a><ul class="vp-sidebar-sub-headers"><li class="vp-sidebar-sub-header"><a aria-label="字符串常量" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#字符串常量"><!---->字符串常量<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="数值型常量" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#数值型常量"><!---->数值型常量<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="时间戳常量" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#时间戳常量"><!---->时间戳常量<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="布尔型常量" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#布尔型常量"><!---->布尔型常量<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="空值" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#空值"><!---->空值<!----></a><ul class="vp-sidebar-sub-headers"></ul></li></ul></li><li class="vp-sidebar-sub-header"><a aria-label="标识符" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#标识符"><!---->标识符<!----></a><ul class="vp-sidebar-sub-headers"><li class="vp-sidebar-sub-header"><a aria-label="使用场景" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#使用场景-1"><!---->使用场景<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="约束" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#约束"><!---->约束<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="如何在反引号引起的标识符中使用引号" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#如何在反引号引起的标识符中使用引号"><!---->如何在反引号引起的标识符中使用引号<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="特殊情况示例" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#特殊情况示例"><!---->特殊情况示例<!----></a><ul class="vp-sidebar-sub-headers"></ul></li></ul></li><li class="vp-sidebar-sub-header"><a aria-label="关键字" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#关键字"><!---->关键字<!----></a><ul class="vp-sidebar-sub-headers"></ul></li><li class="vp-sidebar-sub-header"><a aria-label="词法与文法详细定义" class="vp-link nav-link vp-sidebar-link vp-heading nav-link vp-sidebar-link vp-heading" href="/zh/UserGuide/latest/User-Manual/Syntax-Rule.html#词法与文法详细定义"><!---->词法与文法详细定义<!----></a><ul class="vp-sidebar-sub-headers"></ul></li></ul><!--]--></li><li><!--[--><a aria-label="元数据管理" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Operate-Metadata.html"><!---->元数据管理<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="数据增删" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Write-Delete-Data.html"><!---->数据增删<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="数据查询" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Query-Data.html"><!---->数据查询<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="运算符和表达式" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Operator-and-Expression.html"><!---->运算符和表达式<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="流处理" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Streaming.html"><!---->流处理<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="数据同步" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Data-Sync.html"><!---->数据同步<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="数据库编程" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Database-Programming.html"><!---->数据库编程<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-label="权限管理" class="vp-link nav-link vp-sidebar-link vp-sidebar-page nav-link vp-sidebar-link vp-sidebar-page" href="/zh/UserGuide/latest/User-Manual/Authority-Management.html"><!---->权限管理<!----></a><ul class="vp-sidebar-sub-headers"></ul><!--]--></li></ul></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">工具体系</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">应用编程接口</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">系统集成</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">SQL手册</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">FAQ</span><span class="vp-arrow end"></span></button><!----></section></li><li><section class="vp-sidebar-group"><button class="vp-sidebar-heading clickable" type="button"><!----><span class="vp-sidebar-title">参考</span><span class="vp-arrow end"></span></button><!----></section></li></ul><!--[--><!----><!--]--></aside><!--[--><main id="main-content" class="vp-page"><!--[--><!--[--><!----><!--]--><!----><nav class="vp-breadcrumb disable"></nav><div class="vp-page-title"><h1><!---->语法约定</h1><div class="page-info"><!----><!----><span class="page-date-info" aria-label="写作日期"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 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7.637 13.592 4.143 194.44 97.22 354.963 220.201 392.763-122.204 37.542-214.893 196.511-220.2 389.397-4.661 5.049-7.638 11.651-7.638 19.03v5.825h566.49v-5.825c0-7.379-2.849-13.981-7.509-18.9-5.049-193.016-97.867-351.985-220.2-389.527 123.24-37.67 216.446-198.453 220.588-392.892zM531.16 450.445v352.632c117.674 1.553 211.787 40.778 211.787 88.676H304.097c0-48.286 95.149-87.382 213.728-88.676V450.445c-93.077-3.107-167.901-81.297-167.901-177.093 0-8.803 6.99-15.793 15.793-15.793 8.803 0 15.794 6.99 15.794 15.793 0 80.261 63.69 145.635 142.01 145.635s142.011-65.374 142.011-145.635c0-8.803 6.99-15.793 15.794-15.793s15.793 6.99 15.793 15.793c0 95.019-73.789 172.82-165.96 177.093z"></path></svg><span>大约 6 分钟</span><meta property="timeRequired" content="PT6M"></span><!----><!----></div><hr></div><div class="toc-place-holder"><aside id="toc"><!--[--><!----><!--]--><div class="toc-header">此页内容<button type="button" class="print-button" title="打印"><svg xmlns="http://www.w3.org/2000/svg" class="icon print-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="print icon"><path d="M819.2 364.8h-44.8V128c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v236.8h-44.8C145.067 364.8 96 413.867 96 473.6v192c0 59.733 49.067 108.8 108.8 108.8h44.8V896c0 17.067 14.933 32 32 32h460.8c17.067 0 32-14.933 32-32V774.4h44.8c59.733 0 108.8-49.067 108.8-108.8v-192c0-59.733-49.067-108.8-108.8-108.8zM313.6 160h396.8v204.8H313.6V160zm396.8 704H313.6V620.8h396.8V864zM864 665.6c0 25.6-19.2 44.8-44.8 44.8h-44.8V588.8c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v121.6h-44.8c-25.6 0-44.8-19.2-44.8-44.8v-192c0-25.6 19.2-44.8 44.8-44.8h614.4c25.6 0 44.8 19.2 44.8 44.8v192z"></path></svg></button></div><div class="toc-wrapper"><ul class="toc-list"><!--[--><li class="toc-item"><a class="vp-link toc-link level2 toc-link level2" href="#字面值常量">字面值常量</a></li><li><ul class="toc-list"><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#字符串常量">字符串常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#数值型常量">数值型常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#时间戳常量">时间戳常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#布尔型常量">布尔型常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#空值">空值</a></li><!----><!--]--></ul></li><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level2 toc-link level2" href="#标识符">标识符</a></li><li><ul class="toc-list"><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#使用场景-1">使用场景</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#约束">约束</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#如何在反引号引起的标识符中使用引号">如何在反引号引起的标识符中使用引号</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level3 toc-link level3" href="#特殊情况示例">特殊情况示例</a></li><!----><!--]--></ul></li><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level2 toc-link level2" href="#关键字">关键字</a></li><!----><!--]--><!--[--><li class="toc-item"><a class="vp-link toc-link level2 toc-link level2" href="#词法与文法详细定义">词法与文法详细定义</a></li><!----><!--]--></ul><div class="toc-marker" style="top:-1.7rem;"></div></div><!--[--><!----><!--]--></aside></div><!--[--><!----><!--]--><div class="theme-hope-content"><!--
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the License for the
specific language governing permissions and limitations
under the License.
--><h1 id="语法约定" tabindex="-1"><a class="header-anchor" href="#语法约定" aria-hidden="true">#</a> 语法约定</h1><h2 id="字面值常量" tabindex="-1"><a class="header-anchor" href="#字面值常量" aria-hidden="true">#</a> 字面值常量</h2><p>该部分对 IoTDB 中支持的字面值常量进行说明，包括字符串常量、数值型常量、时间戳常量、布尔型常量和空值。</p><h3 id="字符串常量" tabindex="-1"><a class="header-anchor" href="#字符串常量" aria-hidden="true">#</a> 字符串常量</h3><p>在 IoTDB 中，字符串是由<strong>单引号（<code>&#39;</code>）或双引号（<code>&quot;</code>）字符括起来的字符序列</strong>。示例如下：</p><div class="language-Plain%20Text line-numbers-mode" data-ext="Plain%20Text"><pre class="language-Plain%20Text"><code>&#39;a string&#39;
&quot;another string&quot;
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><h4 id="使用场景" tabindex="-1"><a class="header-anchor" href="#使用场景" aria-hidden="true">#</a> 使用场景</h4><ul><li><p><code>INSERT</code> 或者 <code>SELECT</code> 中用于表达 <code>TEXT</code> 类型数据的场景。</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code># insert 示例
insert into root.ln.wf02.wt02(timestamp,hardware) values(1, &#39;v1&#39;)
insert into root.ln.wf02.wt02(timestamp,hardware) values(2, &#39;\\&#39;)
+-----------------------------+--------------------------+
| Time|root.ln.wf02.wt02.hardware|
+-----------------------------+--------------------------+
|1970-01-01T08:00:00.001+08:00| v1|
+-----------------------------+--------------------------+
|1970-01-01T08:00:00.002+08:00| \\|
+-----------------------------+--------------------------+
# select 示例
select code from root.sg1.d1 where code in (&#39;string1&#39;, &#39;string2&#39;);
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p><code>LOAD</code> / <code>REMOVE</code> / <code>SETTLE</code> 指令中的文件路径。</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code># load 示例
LOAD &#39;examplePath&#39;
# remove 示例
REMOVE &#39;examplePath&#39;
# SETTLE 示例
SETTLE &#39;examplePath&#39;
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>用户密码。</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code># 示例，write_pwd 即为用户密码
CREATE USER ln_write_user &#39;write_pwd&#39;
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>触发器和 UDF 中的类全类名，示例如下：</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code># 触发器示例，AS 后使用字符串表示类全类名
CREATE TRIGGER `alert-listener-sg1d1s1`
AFTER INSERT
ON root.sg1.d1.s1
AS &#39;org.apache.iotdb.db.engine.trigger.example.AlertListener&#39;
WITH (
&#39;lo&#39; = &#39;0&#39;,
&#39;hi&#39; = &#39;100.0&#39;
)
# UDF 示例，AS 后使用字符串表示类全类名
CREATE FUNCTION example AS &#39;org.apache.iotdb.udf.UDTFExample&#39;
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>Select 子句中可以为结果集中的值指定别名，别名可以被定义为字符串或者标识符，示例如下：</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code>select s1 as &#39;temperature&#39;, s2 as &#39;speed&#39; from root.ln.wf01.wt01;
# 表头如下所示
+-----------------------------+-----------|-----+
| Time|temperature|speed|
+-----------------------------+-----------|-----+
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>用于表示键值对，键值对的键和值可以被定义成常量（包括字符串）或者标识符，具体请参考键值对章节。</p></li></ul><h4 id="如何在字符串内使用引号" tabindex="-1"><a class="header-anchor" href="#如何在字符串内使用引号" aria-hidden="true">#</a> 如何在字符串内使用引号</h4><ul><li>在单引号引起的字符串内，双引号无需特殊处理。同理，在双引号引起的字符串内，单引号无需特殊处理。</li><li>在单引号引起的字符串里，可以通过双写单引号来表示一个单引号，即单引号 &#39; 可以表示为 &#39;&#39;。</li><li>在双引号引起的字符串里，可以通过双写双引号来表示一个双引号，即双引号 &quot; 可以表示为 &quot;&quot;。</li></ul><p>字符串内使用引号的示例如下：</p><div class="language-Plain%20Text line-numbers-mode" data-ext="Plain%20Text"><pre class="language-Plain%20Text"><code>&#39;string&#39; // string
&#39;&quot;string&quot;&#39; // &quot;string&quot;
&#39;&quot;&quot;string&quot;&quot;&#39; // &quot;&quot;string&quot;&quot;
&#39;&#39;&#39;string&#39; // &#39;string
&quot;string&quot; // string
&quot;&#39;string&#39;&quot; // &#39;string&#39;
&quot;&#39;&#39;string&#39;&#39;&quot; // &#39;&#39;string&#39;&#39;
&quot;&quot;&quot;string&quot; // &quot;string
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="数值型常量" tabindex="-1"><a class="header-anchor" href="#数值型常量" aria-hidden="true">#</a> 数值型常量</h3><p>数值型常量包括整型和浮点型。</p><p>整型常量是一个数字序列。可以以 <code>+</code> 或 <code>-</code> 开头表示正负。例如：<code>1</code>, <code>-1</code>。</p><p>带有小数部分或由科学计数法表示的为浮点型常量，例如：<code>.1</code>, <code>3.14</code>, <code>-2.23</code>, <code>+1.70</code>, <code>1.2E3</code>, <code>1.2E-3</code>, <code>-1.2E3</code>, <code>-1.2E-3</code>。</p><p>在 IoTDB 中，<code>INT32</code> 和 <code>INT64</code> 表示整数类型（计算是准确的），<code>FLOAT</code> 和 <code>DOUBLE</code> 表示浮点数类型（计算是近似的）。</p><p>在浮点上下文中可以使用整数，它会被解释为等效的浮点数。</p><h3 id="时间戳常量" tabindex="-1"><a class="header-anchor" href="#时间戳常量" aria-hidden="true">#</a> 时间戳常量</h3><p>时间戳是一个数据到来的时间点，在 IoTDB 中分为绝对时间戳和相对时间戳。详细信息可参考 <a href="/zh/UserGuide/latest/Basic-Concept/Data-Type.html" class="">数据类型文档</a>。</p><p>特别地，<code>NOW()</code>表示语句开始执行时的服务端系统时间戳。</p><h3 id="布尔型常量" tabindex="-1"><a class="header-anchor" href="#布尔型常量" aria-hidden="true">#</a> 布尔型常量</h3><p>布尔值常量 <code>TRUE</code> 和 <code>FALSE</code> 分别等价于 <code>1</code> 和 <code>0</code>，它们对大小写不敏感。</p><h3 id="空值" tabindex="-1"><a class="header-anchor" href="#空值" aria-hidden="true">#</a> 空值</h3><p><code>NULL</code>值表示没有数据。<code>NULL</code>对大小写不敏感。</p><h2 id="标识符" tabindex="-1"><a class="header-anchor" href="#标识符" aria-hidden="true">#</a> 标识符</h2><h3 id="使用场景-1" tabindex="-1"><a class="header-anchor" href="#使用场景-1" aria-hidden="true">#</a> 使用场景</h3><p>在 IoTDB 中，触发器名称、UDF函数名、元数据模板名称、用户与角色名、连续查询标识、Pipe、PipeSink、键值对中的键和值、别名等可以作为标识符。</p><h3 id="约束" tabindex="-1"><a class="header-anchor" href="#约束" aria-hidden="true">#</a> 约束</h3><p>请注意，此处约束是标识符的通用约束，具体标识符可能还附带其它约束条件，如用户名限制字符数大于等于4，更严格的约束请参考具体标识符相关的说明文档。</p><p><strong>标识符命名有以下约束：</strong></p><ul><li><p>不使用反引号括起的标识符中，允许出现以下字符：</p><ul><li>[ 0-9 a-z A-Z _ ] （字母，数字，下划线）</li><li>[&#39;\u2E80&#39;..&#39;\u9FFF&#39;] （UNICODE 中文字符）</li></ul></li><li><p>标识符允许使用数字开头、不使用反引号括起的标识符不能全部为数字。</p></li><li><p>标识符是大小写敏感的。</p></li><li><p>标识符允许为关键字。</p></li></ul><p><strong>如果出现如下情况，标识符需要使用反引号进行引用：</strong></p><ul><li>标识符包含不允许的特殊字符。</li><li>标识符为实数。</li></ul><h3 id="如何在反引号引起的标识符中使用引号" tabindex="-1"><a class="header-anchor" href="#如何在反引号引起的标识符中使用引号" aria-hidden="true">#</a> 如何在反引号引起的标识符中使用引号</h3><p><strong>在反引号引起的标识符中可以直接使用单引号和双引号。</strong></p><p><strong>在用反引号引用的标识符中，可以通过双写反引号的方式使用反引号，即 ` 可以表示为 ``</strong>，示例如下：</p><div class="language-SQL line-numbers-mode" data-ext="SQL"><pre class="language-SQL"><code># 创建模板 t1`t
create schema template `t1``t`
(temperature FLOAT encoding=RLE, status BOOLEAN encoding=PLAIN compression=SNAPPY)
# 创建模板 t1&#39;t&quot;t
create schema template `t1&#39;t&quot;t`
(temperature FLOAT encoding=RLE, status BOOLEAN encoding=PLAIN compression=SNAPPY)
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="特殊情况示例" tabindex="-1"><a class="header-anchor" href="#特殊情况示例" aria-hidden="true">#</a> 特殊情况示例</h3><p>需要使用反引号进行引用的部分情况示例：</p><ul><li><p>触发器名称出现上述特殊情况时需使用反引号引用：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建触发器 alert.`listener-sg1d1s1</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TRIGGER</span> <span class="token identifier"><span class="token punctuation">`</span>alert.``listener-sg1d1s1<span class="token punctuation">`</span></span>
<span class="token keyword">AFTER</span> <span class="token keyword">INSERT</span>
<span class="token keyword">ON</span> root<span class="token punctuation">.</span>sg1<span class="token punctuation">.</span>d1<span class="token punctuation">.</span>s1
<span class="token keyword">AS</span> <span class="token string">&#39;org.apache.iotdb.db.engine.trigger.example.AlertListener&#39;</span>
<span class="token keyword">WITH</span> <span class="token punctuation">(</span>
<span class="token string">&#39;lo&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;0&#39;</span><span class="token punctuation">,</span>
<span class="token string">&#39;hi&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;100.0&#39;</span>
<span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>UDF 名称出现上述特殊情况时需使用反引号引用：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建名为 111 的 UDF，111 为实数，所以需要用反引号引用。</span>
<span class="token keyword">CREATE</span> <span class="token keyword">FUNCTION</span> <span class="token identifier"><span class="token punctuation">`</span>111<span class="token punctuation">`</span></span> <span class="token keyword">AS</span> <span class="token string">&#39;org.apache.iotdb.udf.UDTFExample&#39;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>元数据模板名称出现上述特殊情况时需使用反引号引用：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建名为 111 的元数据模板，111 为实数，需要用反引号引用。</span>
<span class="token keyword">create</span> <span class="token keyword">schema</span> template <span class="token identifier"><span class="token punctuation">`</span>111<span class="token punctuation">`</span></span>
<span class="token punctuation">(</span>temperature <span class="token keyword">FLOAT</span> encoding<span class="token operator">=</span>RLE<span class="token punctuation">,</span> <span class="token keyword">status</span> <span class="token keyword">BOOLEAN</span> encoding<span class="token operator">=</span>PLAIN compression<span class="token operator">=</span>SNAPPY<span class="token punctuation">)</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>用户名、角色名出现上述特殊情况时需使用反引号引用，同时无论是否使用反引号引用，用户名、角色名中均不允许出现空格，具体请参考权限管理章节中的说明。</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建用户 special`user.</span>
<span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token identifier"><span class="token punctuation">`</span>special``user.<span class="token punctuation">`</span></span> <span class="token string">&#39;write_pwd&#39;</span>
<span class="token comment"># 创建角色 111</span>
<span class="token keyword">CREATE</span> ROLE <span class="token identifier"><span class="token punctuation">`</span>111<span class="token punctuation">`</span></span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>连续查询标识出现上述特殊情况时需使用反引号引用：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建连续查询 test.cq</span>
<span class="token keyword">CREATE</span> CONTINUOUS QUERY <span class="token identifier"><span class="token punctuation">`</span>test.cq<span class="token punctuation">`</span></span>
<span class="token keyword">BEGIN</span>
<span class="token keyword">SELECT</span> max_value<span class="token punctuation">(</span>temperature<span class="token punctuation">)</span>
<span class="token keyword">INTO</span> temperature_max
<span class="token keyword">FROM</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span><span class="token operator">*</span><span class="token punctuation">.</span><span class="token operator">*</span>
<span class="token keyword">GROUP</span> <span class="token keyword">BY</span> <span class="token keyword">time</span><span class="token punctuation">(</span><span class="token number">10</span>s<span class="token punctuation">)</span>
<span class="token keyword">END</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>Pipe、PipeSink 名称出现上述特殊情况时需使用反引号引用：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment"># 创建 PipeSink test.*1</span>
<span class="token keyword">CREATE</span> PIPESINK <span class="token identifier"><span class="token punctuation">`</span>test.*1<span class="token punctuation">`</span></span> <span class="token keyword">AS</span> IoTDB <span class="token punctuation">(</span><span class="token string">&#39;ip&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;输入你的IP&#39;</span><span class="token punctuation">)</span>
<span class="token comment"># 创建 Pipe test.*2</span>
<span class="token keyword">CREATE</span> PIPE <span class="token identifier"><span class="token punctuation">`</span>test.*2<span class="token punctuation">`</span></span> <span class="token keyword">TO</span> <span class="token identifier"><span class="token punctuation">`</span>test.*1<span class="token punctuation">`</span></span> <span class="token keyword">FROM</span>
<span class="token punctuation">(</span><span class="token keyword">select</span> <span class="token operator">*</span><span class="token operator">*</span> <span class="token keyword">from</span> root <span class="token keyword">WHERE</span> <span class="token keyword">time</span><span class="token operator">&gt;=</span>yyyy<span class="token operator">-</span>mm<span class="token operator">-</span>dd HH:MM:SS<span class="token punctuation">)</span> <span class="token keyword">WITH</span> <span class="token string">&#39;SyncDelOp&#39;</span> <span class="token operator">=</span> <span class="token string">&#39;true&#39;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>Select 子句中可以结果集中的值指定别名，别名可以被定义为字符串或者标识符，示例如下：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> s1 <span class="token keyword">as</span> temperature<span class="token punctuation">,</span> s2 <span class="token keyword">as</span> speed <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">;</span>
<span class="token comment"># 表头如下所示</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+-----------+-----+</span>
<span class="token operator">|</span> <span class="token keyword">Time</span><span class="token operator">|</span>temperature<span class="token operator">|</span>speed<span class="token operator">|</span>
<span class="token operator">+</span><span class="token comment">-----------------------------+-----------+-----+</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div></li><li><p>用于表示键值对，键值对的键和值可以被定义成常量（包括字符串）或者标识符，具体请参考键值对章节。</p></li><li><p>路径中非database的节点允许含有“<em>”符号，在使用时需要把该节点用反引号括起来，如root.db.<code>*</code>，但是此种用法只建议在路径中不可避免含有“</em>”时使用。</p></li></ul><h2 id="关键字" tabindex="-1"><a class="header-anchor" href="#关键字" aria-hidden="true">#</a> 关键字</h2><p>关键字是在 SQL 具有特定含义的词，可以作为标识符。保留字是关键字的一个子集，保留字不能用于标识符。</p><p>关于 IoTDB 的关键字列表，可以查看 <a href="https://iotdb.apache.org/zh/UserGuide/Master/Reference/Keywords.html" target="_blank" rel="noopener noreferrer">关键字<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span></a> 。</p><h2 id="词法与文法详细定义" tabindex="-1"><a class="header-anchor" href="#词法与文法详细定义" aria-hidden="true">#</a> 词法与文法详细定义</h2><p>请阅读代码仓库中的词法和语法描述文件：</p><p>词法文件：<code>antlr/src/main/antlr4/org/apache/iotdb/db/qp/sql/IoTDBSqlLexer.g4</code></p><p>语法文件：<code>antlr/src/main/antlr4/org/apache/iotdb/db/qp/sql/IoTDBSqlParser.g4</code></p></div><!--[--><!----><!--]--><footer class="page-meta"><div class="meta-item edit-link"><a href="https://github.com/apache/iotdb-docs/edit/main/src/zh/UserGuide/latest/User-Manual/Syntax-Rule.md" rel="noopener noreferrer" target="_blank" aria-label="发现错误？在 GitHub 上编辑此页" class="nav-link label"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->发现错误？在 GitHub 上编辑此页<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="meta-item git-info"><div class="update-time"><span class="label">上次编辑于: </span><!----></div><div class="contributors"><span class="label">贡献者: </span><!--[--><!--[--><span class="contributor" title="email: 105700158+wanghui42@users.noreply.github.com">wanghui42</span><!--]--><!--]--></div></div></footer><nav class="vp-page-nav"><!----><a aria-label="元数据管理" class="vp-link nav-link next nav-link next" href="/zh/UserGuide/latest/User-Manual/Operate-Metadata.html"><div class="hint">下一页<span class="arrow end"></span></div><div class="link">元数据管理<!----></div></a></nav><!----><!--[--><!----><!--]--><!--]--></main><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">latest</span><p style="text-align:center;color:#909399;font-size:12px;margin:0 30px;">Copyright © 2024 The Apache Software Foundation.<br> Apache and the Apache feather logo are trademarks of The Apache Software Foundation</p><p style="text-align:center;margin-top:10px;color:#909399;font-size:12px;margin:0 30px;"><strong>Have a question?</strong> Connect with us on QQ, WeChat, or Slack. <a href="https://github.com/apache/iotdb/issues/1995">Join the community</a> now.</p></footer></div><!--]--><!--]--><!----><!--]--></div>
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