| <!DOCTYPE html> |
| <html lang="zh-CN" data-theme="light"> |
| <head> |
| <meta charset="utf-8" /> |
| <meta name="viewport" content="width=device-width,initial-scale=1" /> |
| <meta name="generator" content="VuePress 2.0.0-beta.61" /> |
| <meta name="theme" content="VuePress Theme Hope" /> |
| <link rel="alternate" hreflang="en-us" href="https://iotdb.apache.org/UserGuide/V0.13.x/Reference/Syntax-Conventions.html"><meta property="og:url" content="https://iotdb.apache.org/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html"><meta property="og:site_name" content="IoTDB Website"><meta property="og:title" content="语法约定"><meta property="og:description" content="字面值常量 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。 字符串常量 字符串是由单引号(')或双引号(")字符括起来的字符序列。示例如下: 字符串字面值的使用场景: INSERT 或者 SELECT 中用于表达 TEXT 类型数据的场景; SQL 中 UDF 和 Trigger 的 Jav..."><meta property="og:type" content="article"><meta property="og:locale" content="zh-CN"><meta property="og:locale:alternate" content="en-US"><script type="application/ld+json">{"@context":"https://schema.org","@type":"Article","headline":"语法约定","image":[""],"dateModified":null,"author":[]}</script><link rel="icon" href="/favicon.ico"><meta name="Description" content="Apache IoTDB: Time Series Database for IoT"><meta name="Keywords" content="TSDB, time series, time series database, IoTDB, IoT database, IoT data management,时序数据库, 时间序列管理, IoTDB, 物联网数据库, 实时数据库, 物联网数据管理, 物联网数据"><meta name="baidu-site-verification" content="wfKETzB3OT"><meta name="google-site-verification" content="mZWAoRY0yj_HAr-s47zHCGHzx5Ju-RVm5wDbPnwQYFo"><title>语法约定 | IoTDB Website</title><meta name="description" content="字面值常量 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。 字符串常量 字符串是由单引号(')或双引号(")字符括起来的字符序列。示例如下: 字符串字面值的使用场景: INSERT 或者 SELECT 中用于表达 TEXT 类型数据的场景; SQL 中 UDF 和 Trigger 的 Jav..."> |
| <style> |
| :root { |
| --bg-color: #fff; |
| } |
| |
| html[data-theme="dark"] { |
| --bg-color: #1d1e1f; |
| } |
| |
| html, |
| body { |
| background: var(--bg-color); |
| } |
| </style> |
| <script> |
| const userMode = localStorage.getItem("vuepress-theme-hope-scheme"); |
| const systemDarkMode = |
| window.matchMedia && |
| window.matchMedia("(prefers-color-scheme: dark)").matches; |
| |
| if (userMode === "dark" || (userMode !== "light" && systemDarkMode)) { |
| document.documentElement.setAttribute("data-theme", "dark"); |
| } |
| </script> |
| <link rel="preload" href="/assets/style-99c5bc89.css" as="style"><link rel="stylesheet" href="/assets/style-99c5bc89.css"> |
| <link rel="modulepreload" href="/assets/app-9856c3c2.js"><link rel="modulepreload" href="/assets/framework-44b8a372.js"><link rel="modulepreload" href="/assets/Syntax-Conventions.html-22a17427.js"><link rel="modulepreload" href="/assets/Syntax-Conventions.html-fba6044e.js"> |
| </head> |
| <body> |
| <div id="app"><!--[--><!--[--><!--[--><span tabindex="-1"></span><a href="#main-content" class="skip-link sr-only">跳至主要內容</a><!--]--><!--[--><div class="theme-container has-toc"><!--[--><header class="navbar hide-icon" id="navbar"><div class="navbar-start"><button class="toggle-sidebar-button" title="Toggle Sidebar"><span class="icon"></span></button><!--[--><!----><!--]--><a href="/zh/" class="brand"><img class="logo" src="/logo.png" alt="IoTDB Website"><!----><span class="site-name hide-in-pad">IoTDB Website</span></a><!--[--><!----><!--]--></div><div class="navbar-center"><!--[--><!----><!--]--><!--[--><!----><!--]--></div><div class="navbar-end"><!--[--><!----><!--]--><div id="docsearch-container"></div><nav class="nav-links"><div class="nav-item hide-in-mobile"><div class="dropdown-wrapper"><button class="dropdown-title" type="button" aria-label="文档"><span class="title"><!---->文档</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="/zh/UserGuide/Master/QuickStart/QuickStart.html" class="nav-link" aria-label="latest"><!---->latest<!----></a></li><li class="dropdown-item"><a href="/zh/UserGuide/V1.2.x/QuickStart/QuickStart.html" class="nav-link" aria-label="v1.2.x"><!---->v1.2.x<!----></a></li><li class="dropdown-item"><a href="/zh/UserGuide/V1.1.x/QuickStart/QuickStart.html" class="nav-link" aria-label="v1.1.x"><!---->v1.1.x<!----></a></li><li class="dropdown-item"><a href="/zh/UserGuide/V1.0.x/QuickStart/QuickStart.html" class="nav-link" aria-label="v1.0.x"><!---->v1.0.x<!----></a></li><li class="dropdown-item"><a href="/zh/UserGuide/V0.13.x/QuickStart/QuickStart.html" class="nav-link" aria-label="v0.13.x"><!---->v0.13.x<!----></a></li></ul></button></div></div><div class="nav-item hide-in-mobile"><a href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=177051872" rel="noopener noreferrer" target="_blank" aria-label="系统设计" class="nav-link"><!---->系统设计<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="nav-item hide-in-mobile"><a href="/zh/Download/" class="nav-link" aria-label="下载"><!---->下载<!----></a></div><div class="nav-item hide-in-mobile"><div class="dropdown-wrapper"><button class="dropdown-title" type="button" aria-label="社区"><span class="title"><!---->社区</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="/zh/Community/About.html" class="nav-link" aria-label="关于社区"><!---->关于社区<!----></a></li><li class="dropdown-item"><a href="https://cwiki.apache.org/confluence/display/iotdb" rel="noopener noreferrer" target="_blank" aria-label="Wiki" class="nav-link"><!---->Wiki<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></li><li class="dropdown-item"><a href="/zh/Community/Community-Project-Committers.html" class="nav-link" aria-label="开发人员"><!---->开发人员<!----></a></li><li class="dropdown-item"><a href="/zh/Community/Community-Powered-By.html" class="nav-link" aria-label="技术支持"><!---->技术支持<!----></a></li><li class="dropdown-item"><a href="/Community/Materials.html" class="nav-link" aria-label="活动与报告"><!---->活动与报告<!----></a></li><li class="dropdown-item"><a href="/zh/Community/Feedback.html" class="nav-link" aria-label="交流与反馈"><!---->交流与反馈<!----></a></li></ul></button></div></div><div class="nav-item hide-in-mobile"><div class="dropdown-wrapper"><button class="dropdown-title" type="button" aria-label="开发"><span class="title"><!---->开发</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="/zh/Development/VoteRelease.html" class="nav-link" aria-label="如何投票"><!---->如何投票<!----></a></li><li class="dropdown-item"><a href="/zh/Development/HowToCommit.html" class="nav-link" aria-label="如何提交代码"><!---->如何提交代码<!----></a></li><li class="dropdown-item"><a href="/zh/Development/HowToJoin.html" class="nav-link" aria-label="成为Contributor"><!---->成为Contributor<!----></a></li><li class="dropdown-item"><a href="/zh/Development/Committer.html" class="nav-link" aria-label="成为Committer"><!---->成为Committer<!----></a></li><li class="dropdown-item"><a href="/zh/Development/ContributeGuide.html" class="nav-link" aria-label="项目开发指南"><!---->项目开发指南<!----></a></li><li class="dropdown-item"><a href="/zh/Development/HowtoContributeCode.html" class="nav-link" aria-label="技术贡献指南"><!---->技术贡献指南<!----></a></li><li class="dropdown-item"><a href="/zh/Development/format-changelist.html" class="nav-link" aria-label="TsFile的更改列表"><!---->TsFile的更改列表<!----></a></li><li class="dropdown-item"><a href="/zh/Development/rpc-changelist" class="nav-link" aria-label="RPC变更清单"><!---->RPC变更清单<!----></a></li></ul></button></div></div><div class="nav-item hide-in-mobile"><div class="dropdown-wrapper"><button class="dropdown-title" type="button" aria-label="ASF"><span class="title"><!---->ASF</span><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="https://www.apache.org/" rel="noopener noreferrer" target="_blank" aria-label="基金会" class="nav-link"><!---->基金会<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></li><li class="dropdown-item"><a href="https://www.apache.org/licenses/" rel="noopener noreferrer" target="_blank" aria-label="许可证" class="nav-link"><!---->许可证<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></li><li class="dropdown-item"><a href="https://www.apache.org/security/" rel="noopener noreferrer" target="_blank" aria-label="安全" class="nav-link"><!---->安全<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></li><li class="dropdown-item"><a href="https://www.apache.org/foundation/sponsorship.html" rel="noopener noreferrer" target="_blank" aria-label="赞助" class="nav-link"><!---->赞助<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></li><li class="dropdown-item"><a href="https://www.apache.org/foundation/thanks.html" rel="noopener noreferrer" target="_blank" aria-label="致谢" class="nav-link"><!---->致谢<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></li><li class="dropdown-item"><a href="https://www.apache.org/events/current-event" rel="noopener noreferrer" target="_blank" aria-label="活动" class="nav-link"><!---->活动<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></li></ul></button></div></div></nav><div class="nav-item"><div class="dropdown-wrapper i18n-dropdown"><button class="dropdown-title" type="button" aria-label="选择语言"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon i18n-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="i18n icon" style="width:1rem;height:1rem;vertical-align:middle;"><path d="M379.392 460.8 494.08 575.488l-42.496 102.4L307.2 532.48 138.24 701.44l-71.68-72.704L234.496 460.8l-45.056-45.056c-27.136-27.136-51.2-66.56-66.56-108.544h112.64c7.68 14.336 16.896 27.136 26.112 35.84l45.568 46.08 45.056-45.056C382.976 312.32 409.6 247.808 409.6 204.8H0V102.4h256V0h102.4v102.4h256v102.4H512c0 70.144-37.888 161.28-87.04 210.944L378.88 460.8zM576 870.4 512 1024H409.6l256-614.4H768l256 614.4H921.6l-64-153.6H576zM618.496 768h196.608L716.8 532.48 618.496 768z"></path></svg><!--]--><span class="arrow"></span><ul class="nav-dropdown"><li class="dropdown-item"><a href="/UserGuide/V0.13.x/Reference/Syntax-Conventions.html" class="nav-link" aria-label="English"><!---->English<!----></a></li><li class="dropdown-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html" class="router-link-active router-link-exact-active nav-link active" aria-label="简体中文"><!---->简体中文<!----></a></li></ul></button></div></div><div class="nav-item hide-in-mobile"><button id="appearance-switch"><svg xmlns="http://www.w3.org/2000/svg" class="icon auto-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="auto icon" style="display:block;"><path d="M512 992C246.92 992 32 777.08 32 512S246.92 32 512 32s480 214.92 480 480-214.92 480-480 480zm0-840c-198.78 0-360 161.22-360 360 0 198.84 161.22 360 360 360s360-161.16 360-360c0-198.78-161.22-360-360-360zm0 660V212c165.72 0 300 134.34 300 300 0 165.72-134.28 300-300 300z"></path></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="dark icon" style="display:none;"><path d="M524.8 938.667h-4.267a439.893 439.893 0 0 1-313.173-134.4 446.293 446.293 0 0 1-11.093-597.334A432.213 432.213 0 0 1 366.933 90.027a42.667 42.667 0 0 1 45.227 9.386 42.667 42.667 0 0 1 10.24 42.667 358.4 358.4 0 0 0 82.773 375.893 361.387 361.387 0 0 0 376.747 82.774 42.667 42.667 0 0 1 54.187 55.04 433.493 433.493 0 0 1-99.84 154.88 438.613 438.613 0 0 1-311.467 128z"></path></svg><svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="light icon" style="display:none;"><path d="M952 552h-80a40 40 0 0 1 0-80h80a40 40 0 0 1 0 80zM801.88 280.08a41 41 0 0 1-57.96-57.96l57.96-58a41.04 41.04 0 0 1 58 58l-58 57.96zM512 752a240 240 0 1 1 0-480 240 240 0 0 1 0 480zm0-560a40 40 0 0 1-40-40V72a40 40 0 0 1 80 0v80a40 40 0 0 1-40 40zm-289.88 88.08-58-57.96a41.04 41.04 0 0 1 58-58l57.96 58a41 41 0 0 1-57.96 57.96zM192 512a40 40 0 0 1-40 40H72a40 40 0 0 1 0-80h80a40 40 0 0 1 40 40zm30.12 231.92a41 41 0 0 1 57.96 57.96l-57.96 58a41.04 41.04 0 0 1-58-58l58-57.96zM512 832a40 40 0 0 1 40 40v80a40 40 0 0 1-80 0v-80a40 40 0 0 1 40-40zm289.88-88.08 58 57.96a41.04 41.04 0 0 1-58 58l-57.96-58a41 41 0 0 1 57.96-57.96z"></path></svg></button></div><div class="nav-item"><a class="repo-link" href="https://github.com/apache/iotdb" target="_blank" rel="noopener noreferrer" aria-label="GitHub"><svg xmlns="http://www.w3.org/2000/svg" class="icon github-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="github icon" style="width:1.25rem;height:1.25rem;vertical-align:middle;"><path d="M511.957 21.333C241.024 21.333 21.333 240.981 21.333 512c0 216.832 140.544 400.725 335.574 465.664 24.49 4.395 32.256-10.07 32.256-23.083 0-11.69.256-44.245 0-85.205-136.448 29.61-164.736-64.64-164.736-64.64-22.315-56.704-54.4-71.765-54.4-71.765-44.587-30.464 3.285-29.824 3.285-29.824 49.195 3.413 75.179 50.517 75.179 50.517 43.776 75.008 114.816 53.333 142.762 40.79 4.523-31.66 17.152-53.377 31.19-65.537-108.971-12.458-223.488-54.485-223.488-242.602 0-53.547 19.114-97.323 50.517-131.67-5.035-12.33-21.93-62.293 4.779-129.834 0 0 41.258-13.184 134.912 50.346a469.803 469.803 0 0 1 122.88-16.554c41.642.213 83.626 5.632 122.88 16.554 93.653-63.488 134.784-50.346 134.784-50.346 26.752 67.541 9.898 117.504 4.864 129.834 31.402 34.347 50.474 78.123 50.474 131.67 0 188.586-114.73 230.016-224.042 242.09 17.578 15.232 33.578 44.672 33.578 90.454v135.85c0 13.142 7.936 27.606 32.854 22.87C862.25 912.597 1002.667 728.747 1002.667 512c0-271.019-219.648-490.667-490.71-490.667z"></path></svg></a></div><!--[--><!----><!--]--><button class="toggle-navbar-button" aria-label="Toggle Navbar" aria-expanded="false" aria-controls="nav-screen"><span class="button-container"><span class="button-top"></span><span class="button-middle"></span><span class="button-bottom"></span></span></button></div></header><!----><!--]--><!----><div class="toggle-sidebar-wrapper"><span class="arrow start"></span></div><aside class="sidebar" id="sidebar"><!--[--><!----><!--]--><ul class="sidebar-links"><li><section class="sidebar-group"><p class="sidebar-heading"><!----><span class="title">IoTDB用户手册 (V0.13.x)</span><!----></p><ul class="sidebar-links"></ul></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">IoTDB简介</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">快速上手</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">数据模式与概念</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable active"><!----><span class="title">语法约定</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><!--[--><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html" class="router-link-active router-link-exact-active nav-link active sidebar-link sidebar-page active" aria-label="语法约定"><!---->语法约定<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#字面值常量" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="字面值常量"><!---->字面值常量<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#字符串常量" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="字符串常量"><!---->字符串常量<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#数值型常量" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="数值型常量"><!---->数值型常量<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#时间戳常量" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="时间戳常量"><!---->时间戳常量<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#布尔型常量" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="布尔型常量"><!---->布尔型常量<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#空值" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="空值"><!---->空值<!----></a><ul class="sidebar-sub-headers"></ul></li></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#标识符" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="标识符"><!---->标识符<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#路径节点名" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="路径节点名"><!---->路径节点名<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#关键字和保留字" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="关键字和保留字"><!---->关键字和保留字<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#表达式" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="表达式"><!---->表达式<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#引用符号" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="引用符号"><!---->引用符号<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#双引号-、单引号" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="双引号(")、单引号(')"><!---->双引号(")、单引号(')<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#反引号" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="反引号(`)"><!---->反引号(`)<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#反斜杠" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="反斜杠(\)"><!---->反斜杠(\)<!----></a><ul class="sidebar-sub-headers"></ul></li></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#了解更多" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="了解更多"><!---->了解更多<!----></a><ul class="sidebar-sub-headers"></ul></li></ul><!--]--></li></ul></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">应用编程接口</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">元数据操作</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">数据写入和删除</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">数据查询</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">数据处理</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">权限管理</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">运维工具</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">系统集成</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">UDF 资料库</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">参考</span><span class="arrow end"></span></button><!----></section></li></ul><!--[--><!----><!--]--></aside><!--[--><main class="page" id="main-content"><!--[--><!----><nav class="breadcrumb disable"></nav><div class="page-title"><h1><!---->语法约定</h1><div class="page-info"><!----><!----><!----><!----><span class="page-reading-time-info" aria-label="阅读时间"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon"><path d="M799.387 122.15c4.402-2.978 7.38-7.897 7.38-13.463v-1.165c0-8.933-7.38-16.312-16.312-16.312H256.33c-8.933 0-16.311 7.38-16.311 16.312v1.165c0 5.825 2.977 10.874 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 7 分钟</span><meta property="timeRequired" content="PT7M"></span><!----><!----></div><hr></div><div class="toc-place-holder"><aside id="toc"><!--[--><!----><!--]--><div class="toc-header">此页内容<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 aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#字面值常量" class="router-link-active router-link-exact-active toc-link level2">字面值常量</a></li><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#字符串常量" class="router-link-active router-link-exact-active toc-link level3">字符串常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#数值型常量" class="router-link-active router-link-exact-active toc-link level3">数值型常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#时间戳常量" class="router-link-active router-link-exact-active toc-link level3">时间戳常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#布尔型常量" class="router-link-active router-link-exact-active toc-link level3">布尔型常量</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#空值" class="router-link-active router-link-exact-active toc-link level3">空值</a></li><!----><!--]--></ul><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#标识符" class="router-link-active router-link-exact-active toc-link level2">标识符</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#路径节点名" class="router-link-active router-link-exact-active toc-link level2">路径节点名</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#关键字和保留字" class="router-link-active router-link-exact-active toc-link level2">关键字和保留字</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#表达式" class="router-link-active router-link-exact-active toc-link level2">表达式</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#引用符号" class="router-link-active router-link-exact-active toc-link level2">引用符号</a></li><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#双引号-、单引号" class="router-link-active router-link-exact-active toc-link level3">双引号(")、单引号(')</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#反引号" class="router-link-active router-link-exact-active toc-link level3">反引号(`)</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#反斜杠" class="router-link-active router-link-exact-active toc-link level3">反斜杠(\)</a></li><!----><!--]--></ul><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/zh/UserGuide/V0.13.x/Reference/Syntax-Conventions.html#了解更多" class="router-link-active router-link-exact-active toc-link level2">了解更多</a></li><!----><!--]--></ul></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>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><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/V0.13.x/Data-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><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><p>关于 IoTDB 的关键字和保留字列表,可以查看 <a href="/zh/UserGuide/V0.13.x/Reference/Keywords.html" class="">关键字和保留字</a> 。</p><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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| <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> |
| </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></div><!----><footer class="page-meta"><div class="meta-item edit-link"><a href="https://github.com/apache/iotdb/edit/rel/0.13/docs/zh/UserGuide/Reference/Syntax-Conventions.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></footer><!----><!----><!----><!--]--></main><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">rel/0.13</span><p style="text-align:center;color:#909399;font-size:12px;margin:0 30px;">Copyright © 2023 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><p style="text-align:center;margin-top:10px;color:#909399;font-size:12px;margin:0 30px;"> We use <a href="https://analytics.google.com">Google Analytics</a> to collect anonymous, aggregated usage information. </p></footer></div><!--]--><!--]--><!----><!--]--></div> |
| <script type="module" src="/assets/app-9856c3c2.js" defer></script> |
| </body> |
| </html> |