| import{_ as p,C as c,O as i,P as l,ah as d,Q as e,U as n,ai as o,ae as t,aW as s}from"./framework-62ad666a.js";const r={},u=s(`<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>字符串是由单引号（<code>'</code>）或双引号（<code>"</code>）字符括起来的字符序列。示例如下：</p><div class="language-javascript line-numbers-mode" data-ext="js"><pre class="language-javascript"><code><span class="token string">'a string'</span> |
| <span class="token string">"another string"</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><p>字符串字面值的使用场景：</p><ul><li><code>INSERT</code> 或者 <code>SELECT</code> 中用于表达 <code>TEXT</code> 类型数据的场景</li><li>SQL 中 UDF 和 Trigger 的 Java 类全类名</li><li><code>CREATE TRIGGER</code> 语句中描述触发器属性的键值对</li><li>UDF 函数输入参数中的属性</li><li><code>LOAD</code> / <code>REMOVE</code> / <code>SETTLE</code> 指令中的文件路径</li><li>用户密码</li></ul><p>通过以下几种方式可以在字符串内使用引号：</p><ul><li>在引号前使用转义符 (\\)。</li><li>在单引号括的的字符串内，双引号无需特殊处理。同理，在双引号括的的字符串内，单引号无需特殊处理。</li></ul><p>关于引号和转义字符的使用示例如下：</p><div class="language-javascript line-numbers-mode" data-ext="js"><pre class="language-javascript"><code><span class="token string">'string'</span> <span class="token comment">// string</span> |
| <span class="token string">'"string"'</span> <span class="token comment">// "string"</span> |
| <span class="token string">'""string""'</span> <span class="token comment">// ""string""</span> |
| <span class="token string">'str\\'ing'</span> <span class="token comment">// str'ing</span> |
| <span class="token string">'\\'string'</span> <span class="token comment">// 'string</span> |
| <span class="token string">"string"</span> <span class="token comment">// string</span> |
| <span class="token string">"'string'"</span> <span class="token comment">// 'string'</span> |
| <span class="token string">"''string''"</span> <span class="token comment">// ''string''</span> |
| <span class="token string">"str\\"ing"</span> <span class="token comment">// str"ing</span> |
| <span class="token string">"\\"string"</span> <span class="token comment">// "string</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 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>`,19),k=s(`<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><p>在 IoTDB 中，触发器名称、UDF函数名、元数据模板名称、用户与角色名等被称为标识符。</p><p>标识符命名有以下约束：</p><ul><li>在不含引用的标识符中，允许出现以下字符： <ul><li>[0-9 a-z A-Z _ : @ # $ { }] （字母，数字，部分特殊字符）</li><li>['\\u2E80'..'\\u9FFF'] （UNICODE 中文字符）</li></ul></li><li>标识符允许使用数字开头、允许全部为数字（<strong>不推荐！</strong>）。</li><li>标识符是大小写敏感的。</li><li>注意：用户与角色名对大小写不敏感，并且不允许转义特殊字符。</li></ul><p>如果标识符要包含不允许的特殊字符，或者使用系统关键字，需要用反引号（\`）对标识符进行引用。反引号引用的标识符中出现反引号需要反斜杠转义。</p><p>示例如下：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code>id <span class="token comment">// 合法，被解析为 id</span> |
| ID <span class="token comment">// 合法，被解析为 ID，与 id 不同</span> |
| id0 <span class="token comment">// 合法，被解析为 id0</span> |
| _id <span class="token comment">// 合法，被解析为 _id</span> |
| <span class="token number">0</span>id <span class="token comment">// 合法，被解析为 0id</span> |
| <span class="token number">233</span> <span class="token comment">// 合法，被解析为 233 (不推荐！)</span> |
| ab<span class="token operator">!</span> <span class="token comment">// 不合法，包含不被允许的特殊字符</span> |
| <span class="token identifier"><span class="token punctuation">\`</span>ab!<span class="token punctuation">\`</span></span> <span class="token comment">// 合法，被解析为 ab!</span> |
| <span class="token identifier"><span class="token punctuation">\`</span>"ab"<span class="token punctuation">\`</span></span> <span class="token comment">// 合法，被解析为 "ab"</span> |
| <span class="token identifier"><span class="token punctuation">\`</span>a<span class="token punctuation">\`</span></span>b<span class="token identifier"><span class="token punctuation">\`</span> // 不合法，反引号应使用反斜杠进行转义 |
| <span class="token punctuation">\`</span></span>a\\<span class="token punctuation">\`</span>b<span class="token identifier"><span class="token punctuation">\`</span> // 合法，被解析为 a<span class="token punctuation">\`</span></span>b |
| </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></div><h2 id="路径节点名" tabindex="-1"><a class="header-anchor" href="#路径节点名" aria-hidden="true">#</a> 路径节点名</h2><p>我们称一个路径中由 <code>.</code> 分割的部分叫做节点（node name）。</p><p>路径节点名的约束与标识符基本一致，但要额外注意以下几点：</p><ul><li><code>root</code> 只允许出现时间序列的开头，若其他层级出现 <code>root</code>，则无法解析，提示报错。</li><li>无论是否使用反引号引用，路径分隔符（<code>.</code>）都不能出现在路径节点名中。 如果路径节点名中一定要出现 <code>.</code> （不推荐！），需要用单引号或双引号括起。在这种情况下，为避免引发歧义，引号被系统视为节点名的一部分。</li><li>在反引号括起的路径节点名中，单引号和双引号需要使用反斜杠进行转义。</li><li>特别地，如果系统在 Windows 系统上部署，那么存储组层级名称是<strong>大小写不敏感</strong>的。例如，同时创建 <code>root.ln</code> 和 <code>root.LN</code> 是不被允许的。</li></ul><p>示例如下：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span>s1<span class="token operator">+</span>s2<span class="token operator">/</span>s3<span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// 解析失败！</span> |
| |
| <span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token identifier"><span class="token punctuation">\`</span>s1+s2/s3<span class="token punctuation">\`</span></span><span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// root.a.b.\`s1+s2/s3\`.c 将被解析为 Path[root, a, b, s1+s2/s3, c]</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><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token keyword">select</span> <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// 解析失败！</span> |
| |
| <span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token identifier"><span class="token punctuation">\`</span>select<span class="token punctuation">\`</span></span> <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// root.a.b.\`select\` 将被解析为 Path[root, a, b, select]</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><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token identifier"><span class="token punctuation">\`</span>s1.s2<span class="token punctuation">\`</span></span><span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// 解析失败！</span> |
| |
| <span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token string">"s1.s2"</span><span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// root.a.b."s1.s2".c 将被解析为 Path[root, a, b, "s1.s2", c]</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><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token identifier"><span class="token punctuation">\`</span>s1"s2<span class="token punctuation">\`</span></span><span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// 解析失败！</span> |
| |
| <span class="token keyword">CREATE</span> TIMESERIES root<span class="token punctuation">.</span>a<span class="token punctuation">.</span>b<span class="token punctuation">.</span><span class="token identifier"><span class="token punctuation">\`</span>s1\\"s2<span class="token punctuation">\`</span></span><span class="token punctuation">.</span>c <span class="token keyword">WITH</span> DATATYPE<span class="token operator">=</span>INT32<span class="token punctuation">,</span> ENCODING<span class="token operator">=</span>RLE |
| <span class="token comment">// root.a.b.\`s1\\"s2\`.c 将被解析为 Path[root, a, b, s1\\"s2, c]</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><h2 id="关键字和保留字" tabindex="-1"><a class="header-anchor" href="#关键字和保留字" aria-hidden="true">#</a> 关键字和保留字</h2><p>关键字是在 SQL 具有特定含义的词，不能直接用于标识符或路径节点名，需要使用反引号进行转义。保留字是关键字的一个子集，保留字不能用于标识符或路径节点名（即使进行了转义）。</p>`,23),m=s('<h2 id="表达式" tabindex="-1"><a class="header-anchor" href="#表达式" aria-hidden="true">#</a> 表达式</h2><p>IoTDB 支持在 <code>select</code> 子句中执行由数字常量、时间序列、算数运算表达式和时间序列生成函数（包括用户自定义函数）组成的任意嵌套表达式。</p><p>注意：当参与表达式的路径节点名由纯数字、单引号、或双引号组成（不推荐！）时，必须使用反引号（`）括起，以免引起歧义。示例如下：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token comment">-- 存在时间序列： root.sg.d.0, root.sg.d.'a' 和 root.sg."d".b</span>\n<span class="token keyword">select</span> <span class="token number">0</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">.</span>d <span class="token comment">-- 存在歧义，解析失败</span>\n<span class="token keyword">select</span> <span class="token string">'a'</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">.</span>d <span class="token comment">-- 存在歧义，解析失败</span>\n<span class="token keyword">select</span> <span class="token string">"d"</span><span class="token punctuation">.</span>b <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg <span class="token comment">-- 存在歧义，解析失败</span>\n<span class="token keyword">select</span> <span class="token identifier"><span class="token punctuation">`</span>0<span class="token punctuation">`</span></span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">.</span>d <span class="token comment">-- 对时间序列 root.sg.d.0 进行查询</span>\n<span class="token keyword">select</span> <span class="token identifier"><span class="token punctuation">`</span>0<span class="token punctuation">`</span></span> <span class="token operator">+</span> <span class="token number">0</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">.</span>d <span class="token comment">-- 表达式，对时间序列 root.sg.d.0 的每一个查询结果加 0</span>\n<span class="token keyword">select</span> myudf<span class="token punctuation">(</span><span class="token identifier"><span class="token punctuation">`</span>'a'<span class="token punctuation">`</span></span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">.</span>d <span class="token comment">-- 表达式，调用函数 myudf，第一个参数为时间序列 root.sg.d.'a'，第二个参数为字符串常量 'x'</span>\n</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><h2 id="引用符号" tabindex="-1"><a class="header-anchor" href="#引用符号" aria-hidden="true">#</a> 引用符号</h2><h3 id="双引号-、单引号" tabindex="-1"><a class="header-anchor" href="#双引号-、单引号" aria-hidden="true">#</a> 双引号（"）、单引号（'）</h3><p>双引号、单引号的使用场景如下：</p><ol><li>字符串字面值由单引号或双引号括起的字符串表示。</li><li>如果要在路径节点名中使用路径分隔符（<code>.</code>），则需要将路径节点名用单引号或双引号括起。在这种情况下，为避免引发歧义，引号被系统视为节点名的一部分。</li></ol><h3 id="反引号" tabindex="-1"><a class="header-anchor" href="#反引号" aria-hidden="true">#</a> 反引号（`）</h3><p>反引号的使用场景如下：</p><ol><li>在标识符中使用特殊字符时，标识符需要使用反引号括起。</li><li>在路径节点名中使用除路径分隔符之外的特殊字符时，路径节点名需要使用反引号括起。在这种情况下，反引号不会被系统视为节点名的一部分。</li></ol><h3 id="反斜杠" tabindex="-1"><a class="header-anchor" href="#反斜杠" aria-hidden="true">#</a> 反斜杠（\\）</h3><p>反斜杠的使用场景如下：</p><ul><li>在字符串常量中，出现双引号或单引号时，要使用反斜杠进行转义。 <ul><li>如："str\\"ing" 解析为 str"ing、'str\\'ing' 解析为 str'ing。</li></ul></li><li>在标识符中，出现反引号时，要使用反斜杠进行转义。 <ul><li>如：`na\\`me` 解析为 na`me。</li></ul></li><li>在路径节点名中，出现双引号或单引号时，要使用反斜杠进行转义。注意，为了避免歧义，反斜杠会被系统视为节点名的一部分。 <ul><li>如：root.sg1.d1."a\\"b" 解析为 Path[root, sg1, d1, "a\\"b"]、root.sg1.d1.'a\\'b' 解析为 Path[root, sg1, d1, 'a\\'b']、root.sg1.d1.`a\\"b` 解析为 Path[root, sg1, d1, a\\"b]、root.sg1.d1.`a\\'b` 解析为 Path[root, sg1, d1, a\\'b]。</li></ul></li></ul><h2 id="了解更多" tabindex="-1"><a class="header-anchor" href="#了解更多" aria-hidden="true">#</a> 了解更多</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>',18);function h(v,b){const a=c("RouterLink");return i(),l("div",null,[d(` |
| |
| 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. |
| |
| `),u,e("p",null,[n("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 "),o(a,{to:"/zh/UserGuide/V0.13.x/Data-Concept/Data-Type.html"},{default:t(()=>[n("数据类型文档")]),_:1}),n("。")]),k,e("p",null,[n("关于 IoTDB 的关键字和保留字列表，可以查看 "),o(a,{to:"/zh/UserGuide/V0.13.x/Reference/Keywords.html"},{default:t(()=>[n("关键字和保留字")]),_:1}),n(" 。")]),m])}const E=p(r,[["render",h],["__file","Syntax-Conventions.html.vue"]]);export{E as default}; |
