import{_ as o,r as p,o as i,c,b as n,d as s,a as e,w as t,e as l}from"./app-BigCS_CO.js";const r={},u=l(`<h1 id="概述" tabindex="-1"><a class="header-anchor" href="#概述"><span>概述</span></a></h1><p>在 IoTDB 中，使用 <code>SELECT</code> 语句从一条或多条时间序列中查询数据。</p><h2 id="语法定义" tabindex="-1"><a class="header-anchor" href="#语法定义"><span>语法定义</span></a></h2><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">SELECT</span> <span class="token punctuation">[</span><span class="token keyword">LAST</span><span class="token punctuation">]</span> selectExpr <span class="token punctuation">[</span><span class="token punctuation">,</span> selectExpr<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
    <span class="token punctuation">[</span><span class="token keyword">INTO</span> intoItem <span class="token punctuation">[</span><span class="token punctuation">,</span> intoItem<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span>
    <span class="token keyword">FROM</span> prefixPath <span class="token punctuation">[</span><span class="token punctuation">,</span> prefixPath<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
    <span class="token punctuation">[</span><span class="token keyword">WHERE</span> whereCondition<span class="token punctuation">]</span>
    <span class="token punctuation">[</span><span class="token keyword">GROUP</span> <span class="token keyword">BY</span> {
        <span class="token punctuation">(</span><span class="token punctuation">[</span>startTime<span class="token punctuation">,</span> endTime<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">interval</span> <span class="token punctuation">[</span><span class="token punctuation">,</span> slidingStep<span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token operator">|</span>
        <span class="token keyword">LEVEL</span> <span class="token operator">=</span> levelNum <span class="token punctuation">[</span><span class="token punctuation">,</span> levelNum<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token operator">|</span>
        TAGS<span class="token punctuation">(</span>tagKey <span class="token punctuation">[</span><span class="token punctuation">,</span> tagKey<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token punctuation">)</span>
    }<span class="token punctuation">]</span>
    <span class="token punctuation">[</span><span class="token keyword">HAVING</span> havingCondition<span class="token punctuation">]</span>
    <span class="token punctuation">[</span><span class="token keyword">ORDER</span> <span class="token keyword">BY</span> sortKey {<span class="token keyword">ASC</span> <span class="token operator">|</span> <span class="token keyword">DESC</span>}<span class="token punctuation">]</span>
    <span class="token punctuation">[</span>FILL <span class="token punctuation">(</span>{PREVIOUS <span class="token operator">|</span> LINEAR <span class="token operator">|</span> constant}<span class="token punctuation">)</span><span class="token punctuation">]</span>
    <span class="token punctuation">[</span>SLIMIT seriesLimit<span class="token punctuation">]</span> <span class="token punctuation">[</span>SOFFSET seriesOffset<span class="token punctuation">]</span>
    <span class="token punctuation">[</span><span class="token keyword">LIMIT</span> rowLimit<span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">OFFSET</span> rowOffset<span class="token punctuation">]</span>
    <span class="token punctuation">[</span>ALIGN <span class="token keyword">BY</span> {<span class="token keyword">TIME</span> <span class="token operator">|</span> DEVICE}<span class="token punctuation">]</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div 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="语法说明" tabindex="-1"><a class="header-anchor" href="#语法说明"><span>语法说明</span></a></h2><h3 id="select-子句" tabindex="-1"><a class="header-anchor" href="#select-子句"><span><code>SELECT</code> 子句</span></a></h3>`,6),d=n("li",null,[n("code",null,"SELECT"),s(" 子句指定查询的输出，由若干个 "),n("code",null,"selectExpr"),s(" 组成。")],-1),k=n("li",null,[s("每个 "),n("code",null,"selectExpr"),s(" 定义查询结果中的一列或多列，它是一个由时间序列路径后缀、常量、函数和运算符组成的表达式。")],-1),v=n("li",null,[s("支持使用"),n("code",null,"AS"),s("为查询结果集中的列指定别名。")],-1),m=n("code",null,"SELECT",-1),h=n("code",null,"LAST",-1),b=n("h3",{id:"into-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#into-子句"},[n("span",null,[n("code",null,"INTO"),s(" 子句")])])],-1),T=n("li",null,[n("code",null,"SELECT INTO"),s(" 用于将查询结果写入一系列指定的时间序列中。"),n("code",null,"INTO"),s(" 子句指定了查询结果写入的目标时间序列。")],-1),f=l('<h3 id="from-子句" tabindex="-1"><a class="header-anchor" href="#from-子句"><span><code>FROM</code> 子句</span></a></h3><ul><li><code>FROM</code> 子句包含要查询的一个或多个时间序列的路径前缀，支持使用通配符。</li><li>在执行查询时，会将 <code>FROM</code> 子句中的路径前缀和 <code>SELECT</code> 子句中的后缀进行拼接得到完整的查询目标序列。</li></ul><h3 id="where-子句" tabindex="-1"><a class="header-anchor" href="#where-子句"><span><code>WHERE</code> 子句</span></a></h3>',3),w=n("li",null,[n("code",null,"WHERE"),s(" 子句指定了对数据行的筛选条件，由一个 "),n("code",null,"whereCondition"),s(" 组成。")],-1),g=n("li",null,[n("code",null,"whereCondition"),s(" 是一个逻辑表达式，对于要选择的每一行，其计算结果为真。如果没有 "),n("code",null,"WHERE"),s(" 子句，将选择所有行。")],-1),y=n("li",null,[s("在 "),n("code",null,"whereCondition"),s(" 中，可以使用除聚合函数之外的任何 IOTDB 支持的函数和运算符。")],-1),_=n("h3",{id:"group-by-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#group-by-子句"},[n("span",null,[n("code",null,"GROUP BY"),s(" 子句")])])],-1),x=n("li",null,[n("code",null,"GROUP BY"),s(" 子句指定对序列进行分段或分组聚合的方式。")],-1),E=n("li",null,[s("分段聚合是指按照时间维度，针对同时间序列中不同数据点之间的时间关系，对数据在行的方向进行分段，每个段得到一个聚合值。目前仅支持"),n("strong",null,"按时间区间分段"),s("，未来将支持更多分段方式。")],-1),S=n("li",null,[s("分组聚合是指针对不同时间序列，在时间序列的潜在业务属性上分组，每个组包含若干条时间序列，每个组得到一个聚合值。支持"),n("strong",null,"按路径层级分组"),s("和"),n("strong",null,"按序列标签分组"),s("两种分组方式。")],-1),I=n("li",null,"分段聚合和分组聚合可以混合使用。",-1),L=n("h3",{id:"having-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#having-子句"},[n("span",null,[n("code",null,"HAVING"),s(" 子句")])])],-1),O=l("<li><code>HAVING</code> 子句指定了对聚合结果的筛选条件，由一个 <code>havingCondition</code> 组成。</li><li><code>havingCondition</code> 是一个逻辑表达式，对于要选择的聚合结果，其计算结果为真。如果没有 <code>HAVING</code> 子句，将选择所有聚合结果。</li><li><code>HAVING</code> 要和聚合函数以及 <code>GROUP BY</code> 子句一起使用。</li>",3),C=l('<h3 id="order-by-子句" tabindex="-1"><a class="header-anchor" href="#order-by-子句"><span><code>ORDER BY</code> 子句</span></a></h3><ul><li><code>ORDER BY</code> 子句用于指定结果集的排序方式。</li><li>按时间对齐模式下：默认按照时间戳大小升序排列，可以通过 <code>ORDER BY TIME DESC</code> 指定结果集按照时间戳大小降序排列。</li><li>按设备对齐模式下：先按照设备排列，每个设备内部按照时间戳大小升序排列，暂不支持使用 <code>ORDER BY</code> 子句。</li></ul><h3 id="fill-子句" tabindex="-1"><a class="header-anchor" href="#fill-子句"><span><code>FILL</code> 子句</span></a></h3>',3),D=n("li",null,[n("code",null,"FILL"),s(" 子句用于指定数据缺失情况下的填充模式，允许用户按照特定的方法对任何查询的结果集填充空值。")],-1),G=n("h3",{id:"slimit-和-soffset-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#slimit-和-soffset-子句"},[n("span",null,[n("code",null,"SLIMIT"),s(" 和 "),n("code",null,"SOFFSET"),s(" 子句")])])],-1),R=n("li",null,[n("code",null,"SLIMIT"),s(" 指定查询结果的列数，"),n("code",null,"SOFFSET"),s(" 指定查询结果显示的起始列位置。"),n("code",null,"SLIMIT"),s(" 和 "),n("code",null,"SOFFSET"),s(" 仅用于控制值列，对时间列和设备列无效。")],-1),Q=n("h3",{id:"limit-和-offset-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#limit-和-offset-子句"},[n("span",null,[n("code",null,"LIMIT"),s(" 和 "),n("code",null,"OFFSET"),s(" 子句")])])],-1),V=n("li",null,[n("code",null,"LIMIT"),s(" 指定查询结果的行数，"),n("code",null,"OFFSET"),s(" 指定查询结果显示的起始行位置。")],-1),A=n("h3",{id:"align-by-子句",tabindex:"-1"},[n("a",{class:"header-anchor",href:"#align-by-子句"},[n("span",null,[n("code",null,"ALIGN BY"),s(" 子句")])])],-1),B=n("li",null,[s("查询结果集默认"),n("strong",null,"按时间对齐"),s("，包含一列时间列和若干个值列，每一行数据各列的时间戳相同。")],-1),q=n("li",null,[s("除按时间对齐之外，还支持"),n("strong",null,"按设备对齐"),s("，查询结果集包含一列时间列、一列设备列和若干个值列。")],-1),F=l(`<h2 id="sql-示例" tabindex="-1"><a class="header-anchor" href="#sql-示例"><span>SQL 示例</span></a></h2><h3 id="示例1-根据一个时间区间选择一列数据" tabindex="-1"><a class="header-anchor" href="#示例1-根据一个时间区间选择一列数据"><span>示例1：根据一个时间区间选择一列数据</span></a></h3><p>SQL 语句为：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> temperature <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01 <span class="token keyword">where</span> <span class="token keyword">time</span> <span class="token operator">&lt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">08</span>:<span class="token number">00.000</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></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” 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><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+-----------------------------+
|                         Time|root.ln.wf01.wt01.temperature|
+-----------------------------+-----------------------------+
|2017-11-01T00:00:00.000+08:00|                        25.96|
|2017-11-01T00:01:00.000+08:00|                        24.36|
|2017-11-01T00:02:00.000+08:00|                        20.09|
|2017-11-01T00:03:00.000+08:00|                        20.18|
|2017-11-01T00:04:00.000+08:00|                        21.13|
|2017-11-01T00:05:00.000+08:00|                        22.72|
|2017-11-01T00:06:00.000+08:00|                        20.71|
|2017-11-01T00:07:00.000+08:00|                        21.45|
+-----------------------------+-----------------------------+
Total line number = 8
It costs 0.026s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="示例2-根据一个时间区间选择多列数据" tabindex="-1"><a class="header-anchor" href="#示例2-根据一个时间区间选择多列数据"><span>示例2：根据一个时间区间选择多列数据</span></a></h3><p>SQL 语句为：</p><div class="language-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> <span class="token keyword">status</span><span class="token punctuation">,</span> temperature <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01 <span class="token keyword">where</span> <span class="token keyword">time</span> <span class="token operator">&gt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">05</span>:<span class="token number">00.000</span> <span class="token operator">and</span> <span class="token keyword">time</span> <span class="token operator">&lt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">12</span>:<span class="token number">00.000</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></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><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+------------------------+-----------------------------+
|                         Time|root.ln.wf01.wt01.status|root.ln.wf01.wt01.temperature|
+-----------------------------+------------------------+-----------------------------+
|2017-11-01T00:06:00.000+08:00|                   false|                        20.71|
|2017-11-01T00:07:00.000+08:00|                   false|                        21.45|
|2017-11-01T00:08:00.000+08:00|                   false|                        22.58|
|2017-11-01T00:09:00.000+08:00|                   false|                        20.98|
|2017-11-01T00:10:00.000+08:00|                    true|                        25.52|
|2017-11-01T00:11:00.000+08:00|                   false|                        22.91|
+-----------------------------+------------------------+-----------------------------+
Total line number = 6
It costs 0.018s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="示例3-按照多个时间区间选择同一设备的多列数据" tabindex="-1"><a class="header-anchor" href="#示例3-按照多个时间区间选择同一设备的多列数据"><span>示例3：按照多个时间区间选择同一设备的多列数据</span></a></h3><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-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> <span class="token keyword">status</span><span class="token punctuation">,</span> temperature <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln<span class="token punctuation">.</span>wf01<span class="token punctuation">.</span>wt01 <span class="token keyword">where</span> <span class="token punctuation">(</span><span class="token keyword">time</span> <span class="token operator">&gt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">05</span>:<span class="token number">00.000</span> <span class="token operator">and</span> <span class="token keyword">time</span> <span class="token operator">&lt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">12</span>:<span class="token number">00.000</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token punctuation">(</span><span class="token keyword">time</span> <span class="token operator">&gt;=</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T16:<span class="token number">35</span>:<span class="token number">00.000</span> <span class="token operator">and</span> <span class="token keyword">time</span> <span class="token operator">&lt;=</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T16:<span class="token number">37</span>:<span class="token number">00.000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></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：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+------------------------+-----------------------------+
|                         Time|root.ln.wf01.wt01.status|root.ln.wf01.wt01.temperature|
+-----------------------------+------------------------+-----------------------------+
|2017-11-01T00:06:00.000+08:00|                   false|                        20.71|
|2017-11-01T00:07:00.000+08:00|                   false|                        21.45|
|2017-11-01T00:08:00.000+08:00|                   false|                        22.58|
|2017-11-01T00:09:00.000+08:00|                   false|                        20.98|
|2017-11-01T00:10:00.000+08:00|                    true|                        25.52|
|2017-11-01T00:11:00.000+08:00|                   false|                        22.91|
|2017-11-01T16:35:00.000+08:00|                    true|                        23.44|
|2017-11-01T16:36:00.000+08:00|                   false|                        21.98|
|2017-11-01T16:37:00.000+08:00|                   false|                        21.93|
+-----------------------------+------------------------+-----------------------------+
Total line number = 9
It costs 0.018s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="示例4-按照多个时间区间选择不同设备的多列数据" tabindex="-1"><a class="header-anchor" href="#示例4-按照多个时间区间选择不同设备的多列数据"><span>示例4：按照多个时间区间选择不同设备的多列数据</span></a></h3><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-sql line-numbers-mode" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="token keyword">select</span> wf01<span class="token punctuation">.</span>wt01<span class="token punctuation">.</span><span class="token keyword">status</span><span class="token punctuation">,</span> wf02<span class="token punctuation">.</span>wt02<span class="token punctuation">.</span>hardware <span class="token keyword">from</span> root<span class="token punctuation">.</span>ln <span class="token keyword">where</span> <span class="token punctuation">(</span><span class="token keyword">time</span> <span class="token operator">&gt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">05</span>:<span class="token number">00.000</span> <span class="token operator">and</span> <span class="token keyword">time</span> <span class="token operator">&lt;</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T00:<span class="token number">12</span>:<span class="token number">00.000</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token punctuation">(</span><span class="token keyword">time</span> <span class="token operator">&gt;=</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T16:<span class="token number">35</span>:<span class="token number">00.000</span> <span class="token operator">and</span> <span class="token keyword">time</span> <span class="token operator">&lt;=</span> <span class="token number">2017</span><span class="token operator">-</span><span class="token number">11</span><span class="token operator">-</span><span class="token number">01</span>T16:<span class="token number">37</span>:<span class="token number">00.000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></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：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+------------------------+--------------------------+
|                         Time|root.ln.wf01.wt01.status|root.ln.wf02.wt02.hardware|
+-----------------------------+------------------------+--------------------------+
|2017-11-01T00:06:00.000+08:00|                   false|                        v1|
|2017-11-01T00:07:00.000+08:00|                   false|                        v1|
|2017-11-01T00:08:00.000+08:00|                   false|                        v1|
|2017-11-01T00:09:00.000+08:00|                   false|                        v1|
|2017-11-01T00:10:00.000+08:00|                    true|                        v2|
|2017-11-01T00:11:00.000+08:00|                   false|                        v1|
|2017-11-01T16:35:00.000+08:00|                    true|                        v2|
|2017-11-01T16:36:00.000+08:00|                   false|                        v1|
|2017-11-01T16:37:00.000+08:00|                   false|                        v1|
+-----------------------------+------------------------+--------------------------+
Total line number = 9
It costs 0.014s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="示例5-根据时间降序返回结果集" tabindex="-1"><a class="header-anchor" href="#示例5-根据时间降序返回结果集"><span>示例5：根据时间降序返回结果集</span></a></h3><p>IoTDB 支持 <code>order by time</code> 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" data-ext="sql" data-title="sql"><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 punctuation">.</span><span class="token operator">*</span><span class="token operator">*</span> <span class="token keyword">where</span> <span class="token keyword">time</span> <span class="token operator">&gt;</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" aria-hidden="true"><div class="line-number"></div></div></div><p>语句执行的结果为：</p><div class="language-text line-numbers-mode" data-ext="text" data-title="text"><pre class="language-text"><code>+-----------------------------+--------------------------+------------------------+-----------------------------+------------------------+
|                         Time|root.ln.wf02.wt02.hardware|root.ln.wf02.wt02.status|root.ln.wf01.wt01.temperature|root.ln.wf01.wt01.status|
+-----------------------------+--------------------------+------------------------+-----------------------------+------------------------+
|2017-11-07T23:59:00.000+08:00|                        v1|                   false|                        21.07|                   false|
|2017-11-07T23:58:00.000+08:00|                        v1|                   false|                        22.93|                   false|
|2017-11-07T23:57:00.000+08:00|                        v2|                    true|                        24.39|                    true|
|2017-11-07T23:56:00.000+08:00|                        v2|                    true|                        24.44|                    true|
|2017-11-07T23:55:00.000+08:00|                        v2|                    true|                         25.9|                    true|
|2017-11-07T23:54:00.000+08:00|                        v1|                   false|                        22.52|                   false|
|2017-11-07T23:53:00.000+08:00|                        v2|                    true|                        24.58|                    true|
|2017-11-07T23:52:00.000+08:00|                        v1|                   false|                        20.18|                   false|
|2017-11-07T23:51:00.000+08:00|                        v1|                   false|                        22.24|                   false|
|2017-11-07T23:50:00.000+08:00|                        v2|                    true|                         23.7|                    true|
+-----------------------------+--------------------------+------------------------+-----------------------------+------------------------+
Total line number = 10
It costs 0.016s
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="使用方式" tabindex="-1"><a class="header-anchor" href="#使用方式"><span>使用方式</span></a></h2><p>数据查询语句支持在 SQL 命令行终端、JDBC、JAVA / C++ / Python / Go 等编程语言 API、RESTful API 中使用。</p>`,37),N=l(`<li><p>在 JAVA / C++ / Python / Go 等编程语言 API 中执行查询语句，详见应用编程接口一章相应文档。接口原型如下：</p><div class="language-java line-numbers-mode" data-ext="java" data-title="java"><pre class="language-java"><code><span class="token class-name">SessionDataSet</span> <span class="token function">executeQueryStatement</span><span class="token punctuation">(</span><span class="token class-name">String</span> sql<span class="token punctuation">)</span><span class="token punctuation">;</span>
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