assets/Result-Format.html-7cedff0c.js

import{_ as e,O as n,P as s,ah as a,aW as l}from"./framework-62ad666a.js";const t={},i=l(`<h2 id="查询结果集格式" tabindex="-1"><a class="header-anchor" href="#查询结果集格式" aria-hidden="true">#</a> 查询结果集格式</h2><p>在 IoTDB 中，查询结果集默认按照时间对齐，同时支持另外两种结果返回形式：</p><ul><li>设备时间对齐 <code>align by device</code></li><li>时序不对齐 <code>disable align</code></li></ul><p>注意：对齐方式子句只能用于查询语句句尾。</p><h3 id="按设备对齐" tabindex="-1"><a class="header-anchor" href="#按设备对齐" aria-hidden="true">#</a> 按设备对齐</h3><p>在 <code>align by device</code> 对齐方式下，设备名会单独作为一列出现。如果 select 子句中有 <code>n</code> 列，最终结果就会有该 <code>n + 2</code> 列（时间列和设备名字列）。</p><p>SQL 形如：</p><div class="language-sql line-numbers-mode" data-ext="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">&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">01</span>:<span class="token number">00</span> align <span class="token keyword">by</span> device
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果如下：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+-----------------+-----------+------+--------+
|                         Time|           Device|temperature|status|hardware|
+-----------------------------+-----------------+-----------+------+--------+
|2017-11-01T00:00:00.000+08:00|root.ln.wf01.wt01|      25.96|  true|    null|
|2017-11-01T00:01:00.000+08:00|root.ln.wf01.wt01|      24.36|  true|    null|
|1970-01-01T08:00:00.001+08:00|root.ln.wf02.wt02|       null|  true|      v1|
|1970-01-01T08:00:00.002+08:00|root.ln.wf02.wt02|       null| false|      v2|
|2017-11-01T00:00:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
|2017-11-01T00:01:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
+-----------------------------+-----------------+-----------+------+--------+
Total line number = 6
It costs 0.012s
</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="时序不对齐" tabindex="-1"><a class="header-anchor" href="#时序不对齐" aria-hidden="true">#</a> 时序不对齐</h3><p>在 <code>disable align</code> 对齐方式下，如果 select 子句中有 <code>n</code> 列，最终结果就会有该 <code>n * 2</code> 列（时间序列的时间和值）。</p><p>注：时序不对齐方式不能用于聚合查询、空值填充，但可使用 Limit 和 Offset 语句进行分页。</p><p>SQL 形如：</p><div class="language-sql line-numbers-mode" data-ext="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">&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">01</span>:<span class="token number">00</span> <span class="token keyword">disable</span> align
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>结果如下：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+--------------------------+-----------------------------+------------------------+-----------------------------+-----------------------------+-----------------------------+------------------------+
|                         Time|root.ln.wf02.wt02.hardware|                         Time|root.ln.wf02.wt02.status|                         Time|root.ln.wf01.wt01.temperature|                         Time|root.ln.wf01.wt01.status|
+-----------------------------+--------------------------+-----------------------------+------------------------+-----------------------------+-----------------------------+-----------------------------+------------------------+
|1970-01-01T08:00:00.001+08:00|                        v1|1970-01-01T08:00:00.001+08:00|                    true|2017-11-01T00:00:00.000+08:00|                        25.96|2017-11-01T00:00:00.000+08:00|                    true|
|1970-01-01T08:00:00.002+08:00|                        v2|1970-01-01T08:00:00.002+08:00|                   false|2017-11-01T00:01:00.000+08:00|                        24.36|2017-11-01T00:01:00.000+08:00|                    true|
|2017-11-01T00:00:00.000+08:00|                        v2|2017-11-01T00:00:00.000+08:00|                    true|                         null|                         null|                         null|                    null|
|2017-11-01T00:01:00.000+08:00|                        v2|2017-11-01T00:01:00.000+08:00|                    true|                         null|                         null|                         null|                    null|
+-----------------------------+--------------------------+-----------------------------+------------------------+-----------------------------+-----------------------------+-----------------------------+------------------------+
Total line number = 4
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></div>`,17);function r(o,d){return n(),s("div",null,[a(`

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`),i])}const p=e(t,[["render",r],["__file","Result-Format.html.vue"]]);export{p as default};