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| <span><svg 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" class="icon outbound"><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="sr-only">(opens new window)</span></span></a></nav> <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>IoTDB用户手册 (V0.11.x)</span> <!----></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>开始</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>概述</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>概念</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>服务器端</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>客户端</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading open"><span>操作指南</span> <span class="arrow down"></span></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/zh/UserGuide/V0.11.x/Operation Manual/DDL Data Definition Language.html" class="sidebar-link">DDL (数据定义语言)</a></li><li><a href="/zh/UserGuide/V0.11.x/Operation Manual/DML Data Manipulation Language.html" class="active sidebar-link">DML (数据操作语言)</a></li><li><a href="/zh/UserGuide/V0.11.x/Operation Manual/Administration.html" class="sidebar-link">权限管理语句</a></li><li><a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html" class="sidebar-link">SQL 参考文档</a></li></ul></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>系统工具</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>生态集成</span> <span class="arrow right"></span></p> <!----></section></li><li><section class="sidebar-group collapsable depth-0"><p class="sidebar-heading"><span>系统设计</span> <span class="arrow right"></span></p> <!----></section></li></ul> </aside> <main class="page"> <div class="content content__default"><h1 id="dml-数据操作语言"><a href="#dml-数据操作语言" class="header-anchor">#</a> DML (数据操作语言)</h1> <h2 id="数据接入"><a href="#数据接入" class="header-anchor">#</a> 数据接入</h2> <p>IoTDB为用户提供多种插入实时数据的方式，例如在<a href="/zh/UserGuide/V0.11.x/Client/Command Line Interface.html">Cli/Shell工具</a>中直接输入插入数据的INSERT语句，或使用Java API（标准<a href="/zh/UserGuide/V0.11.x/Client/Programming - JDBC.html">Java JDBC</a>接口）单条或批量执行插入数据的INSERT语句。</p> <p>本节主要为您介绍实时数据接入的INSERT语句在场景中的实际使用示例，有关INSERT SQL语句的详细语法请参见本文<a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">INSERT语句</a>节。</p> <h3 id="使用insert语句"><a href="#使用insert语句" class="header-anchor">#</a> 使用INSERT语句</h3> <p>使用INSERT语句可以向指定的已经创建的一条或多条时间序列中插入数据。对于每一条数据，均由一个时间戳类型的时间戳和一个数值或布尔值、字符串类型的传感器采集值组成。</p> <p>在本节的场景实例下，以其中的两个时间序列<code>root.ln.wf02.wt02.status</code>和<code>root.ln.wf02.wt02.hardware</code>为例 ，它们的数据类型分别为BOOLEAN和TEXT。</p> <p>单列数据插入示例代码如下：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB > insert into root.ln.wf02.wt02(timestamp,status) values(1,true) |
| IoTDB > insert into root.ln.wf02.wt02(timestamp,hardware) values(1, "v1") |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>以上示例代码将长整型的timestamp以及值为true的数据插入到时间序列<code>root.ln.wf02.wt02.status</code>中和将长整型的timestamp以及值为”v1”的数据插入到时间序列<code>root.ln.wf02.wt02.hardware</code>中。执行成功后会返回执行时间，代表数据插入已完成。</p> <blockquote><p>注意：在IoTDB中，TEXT类型的数据单双引号都可以来表示,上面的插入语句是用的是双引号表示TEXT类型数据，下面的示例将使用单引号表示TEXT类型数据。</p></blockquote> <p>INSERT语句还可以支持在同一个时间点下多列数据的插入，同时向2时间点插入上述两个时间序列的值，多列数据插入示例代码如下：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB > insert into root.ln.wf02.wt02(timestamp, status, hardware) VALUES (2, false, 'v2') |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>插入数据后我们可以使用SELECT语句简单查询已插入的数据。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB > select * from root.ln.wf02 where time < 3 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>结果如图所示。由查询结果可以看出，单列、多列数据的插入操作正确执行。 |
| <center><img src="https://user-images.githubusercontent.com/13203019/51605021-c2ee1500-1f48-11e9-8f6b-ba9b48875a41.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center></p> <h3 id="insert语句的错误处理"><a href="#insert语句的错误处理" class="header-anchor">#</a> INSERT语句的错误处理</h3> <p>若用户向一个不存在的时间序列中插入数据，例如执行以下命令：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB > insert into root.ln.wf02.wt02(timestamp, temperature) values(1,"v1") |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>由于<code>root.ln.wf02.wt02. temperature</code>时间序列不存在，系统将会返回以下ERROR告知该Timeseries路径不存在：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>Msg: The resultDataType or encoding or compression of the last node temperature is conflicting in the storage group root.ln |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>若用户插入的数据类型与该Timeseries对应的数据类型不一致，例如执行以下命令：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB > insert into root.ln.wf02.wt02(timestamp,hardware) values(1,100) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>系统将会返回以下ERROR告知数据类型有误：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>error: The TEXT data type should be covered by " or ' |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><h2 id="数据查询"><a href="#数据查询" class="header-anchor">#</a> 数据查询</h2> <h3 id="时间切片查询"><a href="#时间切片查询" class="header-anchor">#</a> 时间切片查询</h3> <p>本节主要介绍时间切片查询的相关示例，主要使用的是<a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">IoTDB SELECT语句</a>。同时，您也可以使用<a href="/zh/UserGuide/V0.11.x/Client/Programming - JDBC.html">Java JDBC</a>标准接口来执行相关的查询语句。</p> <h4 id="根据一个时间区间选择一列数据"><a href="#根据一个时间区间选择一列数据" class="header-anchor">#</a> 根据一个时间区间选择一列数据</h4> <p>SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select temperature from root.ln.wf01.wt01 where time < 2017-11-01T00:08:00.000 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其含义为：</p> <p>被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为温度传感器（temperature）；该语句要求选择出该设备在“2017-11-01T00:08:00.000”（此处可以使用多种时间格式，详情可参看<a href="/zh/UserGuide/V0.11.x/Concept/Data Model and Terminology.html">2.1节</a>）时间点以前的所有温度传感器的值。</p> <p>该SQL语句的执行结果如下：</p> <center><img src="https://user-images.githubusercontent.com/23614968/61280074-da1c0a00-a7e9-11e9-8eb8-3809428043a8.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="根据一个时间区间选择多列数据"><a href="#根据一个时间区间选择多列数据" class="header-anchor">#</a> 根据一个时间区间选择多列数据</h4> <p>SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status, temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其含义为：</p> <p>被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为供电状态（status）和温度传感器（temperature）；该语句要求选择出“2017-11-01T00:05:00.000”至“2017-11-01T00:12:00.000”之间的所选时间序列的值。</p> <p>该SQL语句的执行结果如下：</p> <center><img src="https://user-images.githubusercontent.com/23614968/61280328-40a12800-a7ea-11e9-85b9-3b8db67673a3.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="按照多个时间区间选择同一设备的多列数据"><a href="#按照多个时间区间选择同一设备的多列数据" class="header-anchor">#</a> 按照多个时间区间选择同一设备的多列数据</h4> <p>IoTDB支持在一次查询中指定多个时间区间条件，用户可以根据需求随意组合时间区间条件。例如，</p> <p>SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where (time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000) or (time >= 2017-11-01T16:35:00.000 and time <= 2017-11-01T16:37:00.000); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其含义为：</p> <p>被选择的设备为ln集团wf01子站wt01设备；被选择的时间序列为“供电状态（status）”和“温度传感器（temperature）”；该语句指定了两个不同的时间区间，分别为“2017-11-01T00:05:00.000至2017-11-01T00:12:00.000”和“2017-11-01T16:35:00.000至2017-11-01T16:37:00.000”；该语句要求选择出满足任一时间区间的被选时间序列的值。</p> <p>该SQL语句的执行结果如下： |
| <center><img src="https://user-images.githubusercontent.com/23614968/61280449-780fd480-a7ea-11e9-8ed0-70fa9dfda80f.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center></p> <h4 id="按照多个时间区间选择不同设备的多列数据"><a href="#按照多个时间区间选择不同设备的多列数据" class="header-anchor">#</a> 按照多个时间区间选择不同设备的多列数据</h4> <p>该系统支持在一次查询中选择任意列的数据，也就是说，被选择的列可以来源于不同的设备。例如，SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select wf01.wt01.status,wf02.wt02.hardware from root.ln where (time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000) or (time >= 2017-11-01T16:35:00.000 and time <= 2017-11-01T16:37:00.000); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其含义为：</p> <p>被选择的时间序列为“ln集团wf01子站wt01设备的供电状态”以及“ln集团wf02子站wt02设备的硬件版本”；该语句指定了两个时间区间，分别为“2017-11-01T00:05:00.000至2017-11-01T00:12:00.000”和“2017-11-01T16:35:00.000至2017-11-01T16:37:00.000”；该语句要求选择出满足任意时间区间的被选时间序列的值。</p> <p>该SQL语句的执行结果如下： |
| <center><img src="https://user-images.githubusercontent.com/13203019/51577450-dcfe0800-1ef4-11e9-9399-4ba2b2b7fb73.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center></p> <h4 id="根据时间降序返回"><a href="#根据时间降序返回" class="header-anchor">#</a> 根据时间降序返回</h4> <p>IoTDB 在 0.11 版本开始支持 'order by time' 语句, 用于对结果按照时间进行降序展示。例如，SQL语句为：</p> <div class="language-sql line-numbers-mode"><pre class="language-sql"><code><span class="token keyword">select</span> <span class="token operator">*</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln <span class="token keyword">where</span> <span class="token keyword">time</span> <span class="token operator">></span> <span class="token number">1</span> <span class="token keyword">order</span> <span class="token keyword">by</span> <span class="token keyword">time</span> <span class="token keyword">desc</span> <span class="token keyword">limit</span> <span class="token number">10</span><span class="token punctuation">;</span> |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>更多语法请参照 <a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">SQL REFERENCE</a>.</p> <h4 id="其他结果返回形式"><a href="#其他结果返回形式" class="header-anchor">#</a> 其他结果返回形式</h4> <p>IoTDB支持另外两种结果返回形式: 按设备时间对齐 'align by device' 和 时序不对齐 'disable align'.</p> <p>'align by device' 对齐方式下，设备ID会单独作为一列出现。在 select 子句中写了多少列，最终结果就会有该列数+2 （时间列和设备名字列）。SQL形如:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select s1,s2 from root.sg1.* GROUP BY DEVICE |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>更多语法请参照 SQL REFERENCE.</p> <p>'disable align' 意味着每条时序就有3列存在。更多语法请参照 SQL REFERENCE.</p> <h3 id="聚合查询"><a href="#聚合查询" class="header-anchor">#</a> 聚合查询</h3> <p>本章节主要介绍聚合查询的相关示例， |
| 主要使用的是IoTDB SELECT语句的聚合查询函数。</p> <h4 id="统计总点数"><a href="#统计总点数" class="header-anchor">#</a> 统计总点数</h4> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><table><thead><tr><th>count(root.ln.wf01.wt01.status)</th></tr></thead> <tbody><tr><td>4</td></tr></tbody></table> <h5 id="按层级统计"><a href="#按层级统计" class="header-anchor">#</a> 按层级统计</h5> <p>通过定义LEVEL来统计指定层级下的数据点个数。</p> <p>这可以用来查询不同层级下的数据点总个数</p> <p>语法是：</p> <p>这个可以用来查询某个路径下的总数据点数</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01 group by level=1; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><table><thead><tr><th>Time</th> <th>count(root.ln)</th></tr></thead> <tbody><tr><td>0</td> <td>7</td></tr></tbody></table> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01 group by level=2; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><table><thead><tr><th>Time</th> <th>count(root.ln.wf01)</th> <th>count(root.ln.wf02)</th></tr></thead> <tbody><tr><td>0</td> <td>4</td> <td>3</td></tr></tbody></table> <h3 id="降频聚合查询"><a href="#降频聚合查询" class="header-anchor">#</a> 降频聚合查询</h3> <p>本章节主要介绍降频聚合查询的相关示例， |
| 主要使用的是IoTDB SELECT语句的<a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">GROUP BY子句</a>， |
| 该子句是IoTDB中用于根据用户给定划分条件对结果集进行划分，并对已划分的结果集进行聚合计算的语句。 |
| IoTDB支持根据时间间隔和自定义的滑动步长（默认值与时间间隔相同，自定义的值必须大于等于时间间隔）对结果集进行划分，默认结果按照时间升序排列。 |
| 同时，您也可以使用Java JDBC标准接口来执行相关的查询语句。</p> <p>GROUP BY语句为用户提供三类指定参数：</p> <ul><li>参数1：时间轴显示时间窗参数</li> <li>参数2：划分时间轴的时间间隔参数（必须为正数）</li> <li>参数3：滑动步长（可选参数，默认值与时间间隔相同，自定义的值必须大于等于时间间隔）</li></ul> <p>三类参数的实际含义已经在图5.2中指出，这三类参数里，第三个参数是可选的。 |
| 接下来，我们将给出三种典型的降频聚合查询的例子： |
| 滑动步长未指定， |
| 指定滑动步长， |
| 带值过滤条件。</p> <center><img src="https://user-images.githubusercontent.com/16079446/69109512-f808bc80-0ab2-11ea-9e4d-b2b2f58fb474.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"> |
| **图 5.2 三类参数的实际含义**</center> <h4 id="未指定滑动步长的降频聚合查询"><a href="#未指定滑动步长的降频聚合查询" class="header-anchor">#</a> 未指定滑动步长的降频聚合查询</h4> <p>对应的SQL语句是:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>这条查询的含义是:</p> <p>由于用户没有指定滑动步长，滑动步长将会被默认设置为跟时间间隔参数相同，也就是<code>1d</code>。</p> <p>上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。</p> <p>上面这个例子的第二个参数是划分时间轴的时间间隔参数，将<code>1d</code>当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[0,1d), [1d, 2d), [2d, 3d)等等。</p> <p>然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天）</p> <p>每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：</p> <center><img src="https://user-images.githubusercontent.com/16079446/69116068-eed51b00-0ac5-11ea-9731-b5a45c5cd224.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="指定滑动步长的降频聚合查询"><a href="#指定滑动步长的降频聚合查询" class="header-anchor">#</a> 指定滑动步长的降频聚合查询</h4> <p>对应的SQL语句是:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01 00:00:00, 2017-11-07 23:00:00), 3h, 1d); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>这条查询的含义是:</p> <p>由于用户指定了滑动步长为<code>1d</code>，GROUP BY语句执行时将会每次把时间间隔往后移动一天的步长，而不是默认的3小时。</p> <p>也就意味着，我们想要取从2017-11-01到2017-11-07每一天的凌晨0点到凌晨3点的数据。</p> <p>上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。</p> <p>上面这个例子的第二个参数是划分时间轴的时间间隔参数，将<code>3h</code>当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[2017-11-01T00:00:00, 2017-11-01T03:00:00), [2017-11-02T00:00:00, 2017-11-02T03:00:00), [2017-11-03T00:00:00, 2017-11-03T03:00:00)等等。</p> <p>上面这个例子的第三个参数是每次时间间隔的滑动步长。</p> <p>然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天的凌晨0点到凌晨3点）</p> <p>每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：</p> <center><img src="https://user-images.githubusercontent.com/16079446/69116083-f85e8300-0ac5-11ea-84f1-59d934eee96e.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="带值过滤条件的降频聚合查询"><a href="#带值过滤条件的降频聚合查询" class="header-anchor">#</a> 带值过滤条件的降频聚合查询</h4> <p>对应的SQL语句是:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status), max_value(temperature) from root.ln.wf01.wt01 where time > 2017-11-01T01:00:00 and temperature > 20 group by([2017-11-01T00:00:00, 2017-11-07T23:00:00), 3h, 1d); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>这条查询的含义是:</p> <p>由于用户指定了滑动步长为<code>1d</code>，GROUP BY语句执行时将会每次把时间间隔往后移动一天的步长，而不是默认的3小时。</p> <p>也就意味着，我们想要取从2017-11-01到2017-11-07每一天的凌晨0点到凌晨3点的数据。</p> <p>上面这个例子的第一个参数是显示窗口参数，决定了最终的显示范围是[2017-11-01T00:00:00, 2017-11-07T23:00:00)。</p> <p>上面这个例子的第二个参数是划分时间轴的时间间隔参数，将<code>3h</code>当作划分间隔，显示窗口参数的起始时间当作分割原点，时间轴即被划分为连续的时间间隔：[2017-11-01T00:00:00, 2017-11-01T03:00:00), [2017-11-02T00:00:00, 2017-11-02T03:00:00), [2017-11-03T00:00:00, 2017-11-03T03:00:00)等等。</p> <p>上面这个例子的第三个参数是每次时间间隔的滑动步长。</p> <p>然后系统将会用WHERE子句中的时间和值过滤条件以及GROUP BY语句中的第一个参数作为数据的联合过滤条件，获得满足所有过滤条件的数据（在这个例子里是在[2017-11-01T00:00:00, 2017-11-07 T23:00:00)这个时间范围的并且满足root.ln.wf01.wt01.temperature > 20的数据），并把这些数据映射到之前分割好的时间轴中（这个例子里是从2017-11-01T00:00:00到2017-11-07T23:00:00:00的每一天的凌晨0点到凌晨3点）</p> <p>每个时间间隔窗口内都有数据，SQL执行后的结果集如下所示：</p> <center><img src="https://user-images.githubusercontent.com/16079446/69116088-001e2780-0ac6-11ea-9a01-dc45271d1dad.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>GROUP BY的SELECT子句里的查询路径必须是聚合函数，否则系统将会抛出如下对应的错误。</p> <center><img src="https://user-images.githubusercontent.com/16079446/69116099-0b715300-0ac6-11ea-8074-84e04797b8c7.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="左开右闭区间"><a href="#左开右闭区间" class="header-anchor">#</a> 左开右闭区间</h4> <p>每个区间的结果时间戳为区间右端点，对应的SQL语句是:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01 group by((5, 40], 5ms); |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>这条查询语句的时间区间是左开右闭的，结果中不会包含时间点5的数据，但是会包含时间点40的数据。</p> <p>SQL执行后的结果集如下所示：</p> <table><thead><tr><th>Time</th> <th>count(root.ln.wf01.wt01.status)</th></tr></thead> <tbody><tr><td>10</td> <td>1</td></tr> <tr><td>15</td> <td>2</td></tr> <tr><td>20</td> <td>3</td></tr> <tr><td>25</td> <td>4</td></tr> <tr><td>30</td> <td>4</td></tr> <tr><td>35</td> <td>3</td></tr> <tr><td>40</td> <td>5</td></tr></tbody></table> <h4 id="降采样后按level聚合查询"><a href="#降采样后按level聚合查询" class="header-anchor">#</a> 降采样后按Level聚合查询</h4> <p>除此之外，还可以通过定义LEVEL来统计指定层级下的数据点个数。</p> <p>例如：</p> <p>统计降采样后的数据点个数</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01 group by ([0,20),3ms), level=1; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><table><thead><tr><th>Time</th> <th>count(root.ln)</th></tr></thead> <tbody><tr><td>0</td> <td>1</td></tr> <tr><td>3</td> <td>0</td></tr> <tr><td>6</td> <td>0</td></tr> <tr><td>9</td> <td>1</td></tr> <tr><td>12</td> <td>3</td></tr> <tr><td>15</td> <td>0</td></tr> <tr><td>18</td> <td>0</td></tr></tbody></table> <p>加上滑动Step的降采样后的结果也可以汇总</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status) from root.ln.wf01.wt01 group by ([0,20),2ms,3ms), level=1; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><table><thead><tr><th>Time</th> <th>count(root.ln)</th></tr></thead> <tbody><tr><td>0</td> <td>1</td></tr> <tr><td>3</td> <td>0</td></tr> <tr><td>6</td> <td>0</td></tr> <tr><td>9</td> <td>0</td></tr> <tr><td>12</td> <td>2</td></tr> <tr><td>15</td> <td>0</td></tr> <tr><td>18</td> <td>0</td></tr></tbody></table> <h4 id="降频聚合查询补空值"><a href="#降频聚合查询补空值" class="header-anchor">#</a> 降频聚合查询补空值</h4> <p>降频聚合出的各个时间段的结果，支持使用前值补空。</p> <p>不允许设置滑动步长，默认为聚合时间区间，实际为定长采样。现在只支持 last_value 聚合函数。</p> <p>目前不支持线性插值补空值。</p> <h5 id="previous-和-previousuntillast-的区别"><a href="#previous-和-previousuntillast-的区别" class="header-anchor">#</a> PREVIOUS 和 PREVIOUSUNTILLAST 的区别</h5> <ul><li>PREVIOUS：只要空值前边有值，就会用其填充空值。</li> <li>PREVIOUSUNTILLAST：不会填充此序列最新点后的空值</li></ul> <p>SQL 示例:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>SELECT last_value(temperature) FROM root.ln.wf01.wt01 GROUP BY([8, 39), 5m) FILL (int32[PREVIOUSUNTILLAST]) |
| SELECT last_value(temperature) FROM root.ln.wf01.wt01 GROUP BY([8, 39), 5m) FILL (int32[PREVIOUSUNTILLAST, 3m]) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>解释:</p> <p>使用 PREVIOUSUNTILLAST 方式填充降频聚合的结果。</p> <p>所有路径必须都伴随聚合函数，否则会报以下错误信息：</p> <center><img src="https://user-images.githubusercontent.com/16079446/69116099-0b715300-0ac6-11ea-8074-84e04797b8c7.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h3 id="最新数据查询"><a href="#最新数据查询" class="header-anchor">#</a> 最新数据查询</h3> <p>SQL语法：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select last <Path> [COMMA <Path>]* from < PrefixPath > [COMMA < PrefixPath >]* <WhereClause> |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>其含义是：查询时间序列prefixPath.path中最近时间戳的数据</p> <p><WhereClause>中当前只支持含有'>'或'>='的时间过滤条件，任何其他过滤条件都将会返回异常。</p> <p>结果集为三列的结构</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>| Time | Path | Value | |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>示例 1：查询 root.ln.wf01.wt01.speed 的最新数据点</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>> select last speed from root.ln.wf01.wt01 |
| |
| | Time | Path | Value | |
| | --- | ----------------------- | ----- | |
| | 5 | root.ln.wf01.wt01.speed | 100 | |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><p>示例 2：查询 root.ln.wf01.wt01 下 speed，status，temperature 时间戳大于等于5的最新数据点。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>> select last speed, status, temperature from root.ln.wf01 where time >= 5 |
| |
| | Time | Path | Value | |
| | --- | ---------------------------- | ----- | |
| | 5 | root.ln.wf01.wt01.speed | 100 | |
| | 7 | root.ln.wf01.wt01.status | true | |
| | 9 | root.ln.wf01.wt01.temperature| 35.7 | |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><h3 id="自动填充"><a href="#自动填充" class="header-anchor">#</a> 自动填充</h3> <p>在IoTDB的实际使用中，当进行时间序列的查询操作时，可能会出现在某些时间点值为null的情况，这会妨碍用户进行进一步的分析。 为了更好地反映数据更改的程度，用户希望可以自动填充缺失值。 因此，IoTDB系统引入了自动填充功能。</p> <p>自动填充功能是指对单列或多列执行时间序列查询时，根据用户指定的方法和有效时间范围填充空值。 如果查询点的值不为null，则填充功能将不起作用。</p> <blockquote><p>注意：在当前版本中，IoTDB为用户提供两种方法：Previous 和Linear。 Previous 方法用前一个值填充空白。 Linear方法通过线性拟合来填充空白。 并且填充功能只能在执行时间点查询时使用。</p></blockquote> <h4 id="填充功能"><a href="#填充功能" class="header-anchor">#</a> 填充功能</h4> <ul><li>Previous功能</li></ul> <p>当查询的时间戳值为空时，将使用前一个时间戳的值来填充空白。 形式化的先前方法如下（有关详细语法，请参见第7.1.3.6节）：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select <path> from <prefixPath> where time = <T> fill(<data_type>[previous, <before_range>], …) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>表3-4给出了所有参数的详细说明。</p> <center>**表3-4previous填充参数列表** |
| <table><thead><tr><th style="text-align:left;">参数名称（不区分大小写）</th> <th style="text-align:left;">解释</th></tr></thead> <tbody><tr><td style="text-align:left;">path, prefixPath</td> <td style="text-align:left;">查询路径； 必填项</td></tr> <tr><td style="text-align:left;">T</td> <td style="text-align:left;">查询时间戳（只能指定一个）； 必填项</td></tr> <tr><td style="text-align:left;">data_type</td> <td style="text-align:left;">填充方法使用的数据类型。 可选值是int32，int64，float，double，boolean，text; 可选字段</td></tr> <tr><td style="text-align:left;">before_range</td> <td style="text-align:left;">表示前一种方法的有效时间范围。 当[T-before \ _range，T]范围内的值存在时，前一种方法将起作用。 如果未指定before_range，则before_range会使用默认值default_fill_interval; -1表示无穷大； 可选字段</td></tr></tbody></table></center> <p>在这里，我们举一个使用先前方法填充空值的示例。 SQL语句如下：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>由于时间根目录root.sgcc.wf03.wt01.temperature在2017-11-01T16：37：50.000为空，因此系统使用以前的时间戳2017-11-01T16：37：00.000（且时间戳位于[2017-11-01T16:36:50.000, 2017-11-01T16:37:50.000]范围）进行填充和显示。</p> <p>在<a href="https://github.com/thulab/iotdb/files/4438687/OtherMaterial-Sample.Data.txt" target="_blank" rel="noopener noreferrer">样例数据中<span><svg 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" class="icon outbound"><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="sr-only">(opens new window)</span></span></a>, 该语句的执行结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577616-67df0280-1ef5-11e9-9dff-2eb8342074eb.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>值得注意的是，如果在指定的有效时间范围内没有值，系统将不会填充空值，如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577679-9f4daf00-1ef5-11e9-8d8b-06a58de6efc1.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>Linear方法</li></ul> <p>当查询的时间戳值为空时，将使用前一个和下一个时间戳的值来填充空白。 形式化线性方法如下：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select <path> from <prefixPath> where time = <T> fill(<data_type>[linear, <before_range>, <after_range>]…) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>表3-5中给出了所有参数的详细说明。</p> <center>**表3-5线性填充参数列表** |
| <table><thead><tr><th style="text-align:left;">参数名称（不区分大小写）</th> <th style="text-align:left;">解释</th></tr></thead> <tbody><tr><td style="text-align:left;">path, prefixPath</td> <td style="text-align:left;">查询路径； 必填项</td></tr> <tr><td style="text-align:left;">T</td> <td style="text-align:left;">查询时间戳（只能指定一个）； 必填项</td></tr> <tr><td style="text-align:left;">data_type</td> <td style="text-align:left;">填充方法使用的数据类型。 可选值是int32，int64，float，double，boolean，text; 可选字段</td></tr> <tr><td style="text-align:left;">before_range, after_range</td> <td style="text-align:left;">表示线性方法的有效时间范围。 当[T-before_range，T + after_range]范围内的值存在时，前一种方法将起作用。 如果未明确指定before_range和after_range，则使用default_fill_interval。 -1表示无穷大； 可选字段</td></tr></tbody></table></center> <p>需要注意的是一旦时间序列在查询时间戳T时刻存在有效值，线性填充就回使用这个值作为结果返回。 |
| 除此之外，如果在[T-before_range，T]或[T, T + after_range]两个范围中任意一个范围内不存在有效填充值，则线性填充返回null值。</p> <p>在这里，我们举一个使用线性方法填充空值的示例。 SQL语句如下：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float [linear, 1m, 1m]) |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>由于时间根目录root.sgcc.wf03.wt01.temperature在2017-11-01T16：37：50.000为空，因此系统使用以前的时间戳2017-11-01T16：37：00.000（且时间戳位于[2017- 11-01T16：36：50.000，2017-11-01T16：37：50.000]时间范围）及其值21.927326，下一个时间戳记2017-11-01T16：38：00.000（且时间戳记位于[2017-11-11] 01T16：37：50.000、2017-11-01T16：38：50.000]时间范围）及其值25.311783以执行线性拟合计算：</p> <p>21.927326 +（25.311783-21.927326）/ 60s * 50s = 24.747707</p> <p>在 <a href="https://github.com/thulab/iotdb/files/4438687/OtherMaterial-Sample.Data.txt" target="_blank" rel="noopener noreferrer">样例数据<span><svg 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" class="icon outbound"><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="sr-only">(opens new window)</span></span></a>, 该语句的执行结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577727-d4f29800-1ef5-11e9-8ff3-3bb519da3993.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="数据类型和填充方法之间的对应关系"><a href="#数据类型和填充方法之间的对应关系" class="header-anchor">#</a> 数据类型和填充方法之间的对应关系</h4> <p>数据类型和支持的填充方法如表3-6所示。</p> <center>**表3-6数据类型和支持的填充方法** |
| <table><thead><tr><th style="text-align:left;">数据类型</th> <th style="text-align:left;">支持的填充方法</th></tr></thead> <tbody><tr><td style="text-align:left;">boolean</td> <td style="text-align:left;">previous</td></tr> <tr><td style="text-align:left;">int32</td> <td style="text-align:left;">previous, linear</td></tr> <tr><td style="text-align:left;">int64</td> <td style="text-align:left;">previous, linear</td></tr> <tr><td style="text-align:left;">float</td> <td style="text-align:left;">previous, linear</td></tr> <tr><td style="text-align:left;">double</td> <td style="text-align:left;">previous, linear</td></tr> <tr><td style="text-align:left;">text</td> <td style="text-align:left;">previous</td></tr></tbody></table></center> <p>值得注意的是，IoTDB将针对数据类型不支持的填充方法给出错误提示，如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577741-e340b400-1ef5-11e9-9238-a4eaf498ab84.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>如果未指定fill方法，则每种数据类型均具有其自己的默认fill方法和参数。 对应关系如表3-7所示。</p> <center>**表3-7各种数据类型的默认填充方法和参数** |
| <table><thead><tr><th style="text-align:left;">数据类型</th> <th style="text-align:left;">默认填充方法和参数</th></tr></thead> <tbody><tr><td style="text-align:left;">boolean</td> <td style="text-align:left;">previous, 600000</td></tr> <tr><td style="text-align:left;">int32</td> <td style="text-align:left;">linear, 600000, 600000</td></tr> <tr><td style="text-align:left;">int64</td> <td style="text-align:left;">linear, 600000, 600000</td></tr> <tr><td style="text-align:left;">float</td> <td style="text-align:left;">linear, 600000, 600000</td></tr> <tr><td style="text-align:left;">double</td> <td style="text-align:left;">linear, 600000, 600000</td></tr> <tr><td style="text-align:left;">text</td> <td style="text-align:left;">previous, 600000</td></tr></tbody></table></center> <blockquote><p>注意：应在Fill语句中至少指定一种填充方法。</p></blockquote> <h3 id="对查询结果的行和列控制"><a href="#对查询结果的行和列控制" class="header-anchor">#</a> 对查询结果的行和列控制</h3> <p>IoTDB提供 <a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">LIMIT/SLIMIT</a> 子句和 <a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">OFFSET/SOFFSET</a> 子句，以使用户可以更好地控制查询结果。使用LIMIT和SLIMIT子句可让用户控制查询结果的行数和列数， |
| 并且使用OFFSET和SOFSET子句允许用户设置结果显示的起始位置。</p> <p>请注意，按组查询不支持LIMIT和OFFSET。</p> <p>本章主要介绍查询结果的行和列控制的相关示例。你还可以使用 <a href="/zh/UserGuide/V0.11.x/Client/Programming - JDBC.html">Java JDBC</a> 标准接口执行查询。</p> <h4 id="查询结果的行控制"><a href="#查询结果的行控制" class="header-anchor">#</a> 查询结果的行控制</h4> <p>通过使用LIMIT和OFFSET子句，用户可以以与行相关的方式控制查询结果。 我们将通过以下示例演示如何使用LIMIT和OFFSET子句。</p> <ul><li>示例1：基本的LIMIT子句</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status, temperature from root.ln.wf01.wt01 limit 10 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回查询结果的前10行。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577752-efc50c80-1ef5-11e9-9071-da2bbd8b9bdd.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例2：带OFFSET的LIMIT子句</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status, temperature from root.ln.wf01.wt01 limit 5 offset 3 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回查询结果的第3至7行（第一行编号为0行）。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577773-08352700-1ef6-11e9-883f-8d353bef2bdc.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例3：LIMIT子句与WHERE子句结合</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time< 2017-11-01T00:12:00.000 limit 2 offset 3 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 选择的时间序列是“状态”和“温度”。 SQL语句要求返回时间“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”之间的状态和温度传感器值的第3至4行（第一行） 编号为第0行）。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577789-15521600-1ef6-11e9-86ca-d7b2c947367f.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例4：LIMIT子句与GROUP BY子句组合</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select count(status), max_value(temperature) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d) limit 5 offset 3 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>SQL语句子句要求返回查询结果的第3至7行（第一行编号为0行）。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577796-1e42e780-1ef6-11e9-8987-be443000a77e.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>值得注意的是，由于当前的FILL子句只能在某个时间点填充时间序列的缺失值，也就是说，FILL子句的执行结果恰好是一行，因此LIMIT和OFFSET不会是 与FILL子句结合使用，否则将提示错误。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select temperature from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) limit 10 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>SQL语句将不会执行，并且相应的错误提示如下：</p> <center><img src="https://user-images.githubusercontent.com/19167280/61517266-6e2fe080-aa39-11e9-8015-154a8e8ace30.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="查询结果的列控制"><a href="#查询结果的列控制" class="header-anchor">#</a> 查询结果的列控制</h4> <p>通过使用LIMIT和OFFSET子句，用户可以以与列相关的方式控制查询结果。 我们将通过以下示例演示如何使用SLIMIT和OFFSET子句。</p> <ul><li>示例1：基本的SLIMIT子句</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第一列，即电源状态。 SQL语句要求在“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”的时间点之间选择状态传感器值。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577813-30bd2100-1ef6-11e9-94ef-dbeb450cf319.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例2：带OFFSET的LIMIT子句</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 soffset 1 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第二列，即温度。 SQL语句要求在“ 2017-11-01T00：05：00.000”和“ 2017-11-01T00：12：00.000”的时间点之间选择温度传感器值。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577827-39adf280-1ef6-11e9-81b5-876769607cd2.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例3：SLIMIT子句与GROUP BY子句结合</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select max_value(*) from root.ln.wf01.wt01 group by ([2017-11-01T00:00:00, 2017-11-07T23:00:00),1d) slimit 1 soffset 1 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577840-44688780-1ef6-11e9-8abc-04ae78efa85b.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <ul><li>示例4：SLIMIT子句与FILL子句结合</li></ul> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select * from root.sgcc.wf03.wt01 where time = 2017-11-01T16:37:50.000 fill(float[previous, 1m]) slimit 1 soffset 1 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 所选时间序列是该设备下的第二列，即温度。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577855-4d595900-1ef6-11e9-8541-a4accd714b75.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>值得注意的是，预期SLIMIT子句将与星形路径或前缀路径一起使用，并且当SLIMIT子句与完整路径查询一起使用时，系统将提示错误。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>SQL语句将不会执行，并且相应的错误提示如下：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577867-577b5780-1ef6-11e9-978c-e02c1294bcc5.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h4 id="控制查询结果的行和列"><a href="#控制查询结果的行和列" class="header-anchor">#</a> 控制查询结果的行和列</h4> <p>除了对查询结果进行行或列控制之外，IoTDB还允许用户控制查询结果的行和列。 这是同时包含LIMIT子句和SLIMIT子句的完整示例。</p> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select * from root.ln.wf01.wt01 limit 10 offset 100 slimit 2 soffset 0 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>意思是：</p> <p>所选设备为ln组wf01工厂wt01设备； 所选时间序列是此设备下的第0列至第1列（第一列编号为第0列）。 SQL语句子句要求返回查询结果的第100至109行（第一行编号为0行）。</p> <p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51577879-64984680-1ef6-11e9-9d7b-57dd60fab60e.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <h3 id="使用别名"><a href="#使用别名" class="header-anchor">#</a> 使用别名</h3> <p>由于 IoTDB 独特的数据模型，在每个传感器前都附带有设备等诸多额外信息。有时，我们只针对某个具体设备查询，而这些前缀信息频繁显示造成了冗余，影响了结果集的显示与分析。这时我们可以使用 IoTDB 提供的 AS 函数，将查询中出现的时间序列给定一个别名。</p> <p>例如：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select s1 as temperature, s2 as speed from root.ln.wf01.wt01; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>则结果集将显示为：</p> <table><thead><tr><th>Time</th> <th>temperature</th> <th>speed</th></tr></thead> <tbody><tr><td>...</td> <td>...</td> <td>...</td></tr></tbody></table> <h4 id="其他结果集格式"><a href="#其他结果集格式" class="header-anchor">#</a> 其他结果集格式</h4> <p>此外，IoTDB支持两种其他结果集格式：“按设备对齐”和“禁用对齐”。</p> <p>“按设备对齐”指示将deviceId视为一列。 因此，数据集中的列完全有限。</p> <p>SQL语句是：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select s1,s2 from root.sg1.* ALIGN BY DEVICE |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>有关更多语法描述，请阅读SQL REFERENCE。</p> <p>“禁用对齐”指示结果集中每个时间序列都有3列。 有关更多语法描述，请阅读SQL REFERENCE。</p> <h4 id="错误处理"><a href="#错误处理" class="header-anchor">#</a> 错误处理</h4> <p>当LIMIT / SLIMIT的参数N / SN超过结果集的大小时，IoTDB将按预期返回所有结果。 例如，原始SQL语句的查询结果由六行组成，我们通过LIMIT子句选择前100行：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 100 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51578187-ad9cca80-1ef7-11e9-897a-83e66a0f3d94.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>当LIMIT / SLIMIT子句的参数N / SN超过允许的最大值（N / SN的类型为int32）时，系统将提示错误。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 1234567890123456789 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>SQL语句将不会执行，并且相应的错误提示如下：</p> <center><img src="https://user-images.githubusercontent.com/19167280/61517469-e696a180-aa39-11e9-8ca5-42ea991d520e.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>当LIMIT / LIMIT子句的参数N / SN不是正整数时，系统将提示错误。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 13.1 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>SQL语句将不会执行，并且相应的错误提示如下：</p> <center><img src="https://user-images.githubusercontent.com/19167280/61518094-68d39580-aa3b-11e9-993c-fc73c27540f7.png" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>当LIMIT子句的参数OFFSET超过结果集的大小时，IoTDB将返回空结果集。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select status,temperature from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 limit 2 offset 6 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>结果如下所示：</p> <center><img src="https://user-images.githubusercontent.com/13203019/51578227-c60ce500-1ef7-11e9-98eb-175beb8d4086.jpg" style="width:100%;max-width:800px;max-height:600px;margin-left:auto;margin-right:auto;display:block;"></center> <p>当SLIMIT子句的参数SOFFSET不小于可用时间序列数时，系统将提示错误。 例如，执行以下SQL语句：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>select * from root.ln.wf01.wt01 where time > 2017-11-01T00:05:00.000 and time < 2017-11-01T00:12:00.000 slimit 1 soffset 2 |
| |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>SQL语句将不会执行，并且相应的错误提示如下：</p> <h3 id="数据删除"><a href="#数据删除" class="header-anchor">#</a> 数据删除</h3> <p>用户使用<a href="/zh/UserGuide/V0.11.x/Operation Manual/SQL Reference.html">DELETE语句</a>可以删除指定的时间序列中符合时间删除条件的数据。在删除数据时，用户可以选择需要删除的一个或多个时间序列、时间序列的前缀、时间序列带*路径对某一个时间区间内的数据进行删除。</p> <p>在JAVA编程环境中，您可以使用JDBC API单条或批量执行DELETE语句。</p> <h4 id="单传感器时间序列值删除"><a href="#单传感器时间序列值删除" class="header-anchor">#</a> 单传感器时间序列值删除</h4> <p>以测控ln集团为例，存在这样的使用场景：</p> <p>wf02子站的wt02设备在2017-11-01 16:26:00之前的供电状态出现多段错误，且无法分析其正确数据，错误数据影响了与其他设备的关联分析。此时，需要将此时间段前的数据删除。进行此操作的SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02.status where time<=2017-11-01T16:26:00; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>如果我们仅仅想要删除2017年内的在2017-11-01 16:26:00之前的数据，可以使用以下SQL:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02.status where time>=2017-01-01T00:00:00 and time<=2017-11-01T16:26:00; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>IoTDB 支持删除一个时间序列任何一个时间范围内的所有时序点，用户可以使用以下SQL语句指定需要删除的时间范围：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02.status where time < 10 |
| delete from root.ln.wf02.wt02.status where time <= 10 |
| delete from root.ln.wf02.wt02.status where time < 20 and time > 10 |
| delete from root.ln.wf02.wt02.status where time <= 20 and time >= 10 |
| delete from root.ln.wf02.wt02.status where time > 20 |
| delete from root.ln.wf02.wt02.status where time >= 20 |
| delete from root.ln.wf02.wt02.status where time = 20 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>需要注意，当前的删除语句不支持where子句后的时间范围为多个由OR连接成的时间区间。如下删除语句将会解析出错：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02.status where time > 4 or time < 0 |
| Msg: 303: Check metadata error: For delete statement, where clause can only contain atomic |
| expressions like : time > XXX, time <= XXX, or two atomic expressions connected by 'AND' |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h4 id="多传感器时间序列值删除"><a href="#多传感器时间序列值删除" class="header-anchor">#</a> 多传感器时间序列值删除</h4> <p>当ln集团wf02子站的wt02设备在2017-11-01 16:26:00之前的供电状态和设备硬件版本都需要删除，此时可以使用含义更广的<a href="/zh/UserGuide/V0.11.x/Concept/Data Model and Terminology.html">前缀路径或带<code>*</code>路径</a>进行删除操作，进行此操作的SQL语句为：</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02 where time <= 2017-11-01T16:26:00; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>或</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>delete from root.ln.wf02.wt02.* where time <= 2017-11-01T16:26:00; |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>需要注意的是，当删除的路径不存在时，IoTDB会提示路径不存在，无法删除数据，如下所示。</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>IoTDB> delete from root.ln.wf03.wt02.status where time < now() |
| Msg: TimeSeries does not exist and its data cannot be deleted |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><h2 id="删除时间分区-实验性功能"><a href="#删除时间分区-实验性功能" class="header-anchor">#</a> 删除时间分区 (实验性功能)</h2> <p>您可以通过如下语句来删除某一个存储组下的指定时间分区:</p> <div class="language- line-numbers-mode"><pre class="language-text"><code>DELETE PARTITION root.ln 0,1,2 |
| </code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><p>上例中的0,1,2为待删除时间分区的id，您可以通过查看IoTDB的数据文件夹找到它，或者可以通过计算<code>timestamp / partitionInterval</code>(向下取整), |
| 手动地将一个时间戳转换为对应的id，其中的<code>partitionInterval</code>可以在IoTDB的配置文件中找到（如果您使用的版本支持时间分区）。</p> <p>请注意该功能目前只是实验性的，如果您不是开发者，使用时请务必谨慎。</p></div> <div class="page-nav"><p class="inner"><span class="prev"> |
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