| import{_ as n,O as s,P as a,ah as e,aW as t}from"./framework-62ad666a.js";const d={},o=t(`<h2 id="聚合函数" tabindex="-1"><a class="header-anchor" href="#聚合函数" aria-hidden="true">#</a> 聚合函数</h2><p>聚合函数是多对一函数。它们对一组值进行聚合计算，得到单个聚合结果。</p><p>除了 <code>COUNT()</code>, <code>COUNT_IF()</code>之外，其他所有聚合函数都忽略空值，并在没有输入行或所有值为空时返回空值。 例如，<code>SUM()</code> 返回 null 而不是零，而 <code>AVG()</code> 在计数中不包括 null 值。</p><p>IoTDB 支持的聚合函数如下：</p><table><thead><tr><th>函数名</th><th>功能描述</th><th>允许的输入类型</th><th>必要的属性参数</th><th>输出类型</th></tr></thead><tbody><tr><td>SUM</td><td>求和。</td><td>INT32 INT64 FLOAT DOUBLE</td><td>无</td><td>DOUBLE</td></tr><tr><td>COUNT</td><td>计算数据点数。</td><td>所有类型</td><td>无</td><td>INT64</td></tr><tr><td>AVG</td><td>求平均值。</td><td>INT32 INT64 FLOAT DOUBLE</td><td>无</td><td>DOUBLE</td></tr><tr><td>EXTREME</td><td>求具有最大绝对值的值。如果正值和负值的最大绝对值相等，则返回正值。</td><td>INT32 INT64 FLOAT DOUBLE</td><td>无</td><td>与输入类型一致</td></tr><tr><td>MAX_VALUE</td><td>求最大值。</td><td>INT32 INT64 FLOAT DOUBLE</td><td>无</td><td>与输入类型一致</td></tr><tr><td>MIN_VALUE</td><td>求最小值。</td><td>INT32 INT64 FLOAT DOUBLE</td><td>无</td><td>与输入类型一致</td></tr><tr><td>FIRST_VALUE</td><td>求时间戳最小的值。</td><td>所有类型</td><td>无</td><td>与输入类型一致</td></tr><tr><td>LAST_VALUE</td><td>求时间戳最大的值。</td><td>所有类型</td><td>无</td><td>与输入类型一致</td></tr><tr><td>MAX_TIME</td><td>求最大时间戳。</td><td>所有类型</td><td>无</td><td>Timestamp</td></tr><tr><td>MIN_TIME</td><td>求最小时间戳。</td><td>所有类型</td><td>无</td><td>Timestamp</td></tr><tr><td>COUNT_IF</td><td>求数据点连续满足某一给定条件，且满足条件的数据点个数（用keep表示）满足指定阈值的次数。</td><td>BOOLEAN</td><td><code>[keep >=/>/=/!=/</<=]threshold</code>：被指定的阈值或阈值条件，若只使用<code>threshold</code>则等价于<code>keep >= threshold</code>,<code>threshold</code>类型为<code>INT64</code><br> <code>ignoreNull</code>：可选，默认为<code>true</code>；为<code>true</code>表示忽略null值，即如果中间出现null值，直接忽略，不会打断连续性；为<code>false</code>表示不忽略null值，即如果中间出现null值，会打断连续性</td><td>INT64</td></tr></tbody></table><h3 id="count-if" tabindex="-1"><a class="header-anchor" href="#count-if" aria-hidden="true">#</a> COUNT_IF</h3><h4 id="语法" tabindex="-1"><a class="header-anchor" href="#语法" aria-hidden="true">#</a> 语法</h4><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code>count_if<span class="token punctuation">(</span>predicate<span class="token punctuation">,</span> <span class="token punctuation">[</span>keep <span class="token operator">>=</span><span class="token operator">/</span><span class="token operator">></span><span class="token operator">/</span><span class="token operator">=</span><span class="token operator">/</span><span class="token operator">!=</span><span class="token operator">/</span><span class="token operator"><</span><span class="token operator">/</span><span class="token operator"><=</span><span class="token punctuation">]</span>threshold<span class="token punctuation">[</span><span class="token punctuation">,</span> <span class="token string">'ignoreNull'</span><span class="token operator">=</span><span class="token string">'true/false'</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>predicate: 返回类型为<code>BOOLEAN</code>的合法表达式</p><p>threshold 及 ignoreNull 用法见上表</p><blockquote><p>注意: count_if 当前暂不支持与 group by time 的 SlidingWindow 一起使用</p></blockquote><h4 id="使用示例" tabindex="-1"><a class="header-anchor" href="#使用示例" aria-hidden="true">#</a> 使用示例</h4><h5 id="原始数据" tabindex="-1"><a class="header-anchor" href="#原始数据" aria-hidden="true">#</a> 原始数据</h5><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+-------------+-------------+ |
| | Time|root.db.d1.s1|root.db.d1.s2| |
| +-----------------------------+-------------+-------------+ |
| |1970-01-01T08:00:00.001+08:00| 0| 0| |
| |1970-01-01T08:00:00.002+08:00| null| 0| |
| |1970-01-01T08:00:00.003+08:00| 0| 0| |
| |1970-01-01T08:00:00.004+08:00| 0| 0| |
| |1970-01-01T08:00:00.005+08:00| 1| 0| |
| |1970-01-01T08:00:00.006+08:00| 1| 0| |
| |1970-01-01T08:00:00.007+08:00| 1| 0| |
| |1970-01-01T08:00:00.008+08:00| 0| 0| |
| |1970-01-01T08:00:00.009+08:00| 0| 0| |
| |1970-01-01T08:00:00.010+08:00| 0| 0| |
| +-----------------------------+-------------+-------------+ |
| </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><h5 id="不使用ignorenull参数-忽略null" tabindex="-1"><a class="header-anchor" href="#不使用ignorenull参数-忽略null" aria-hidden="true">#</a> 不使用ignoreNull参数(忽略null)</h5><p>SQL:</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> count_if<span class="token punctuation">(</span>s1<span class="token operator">=</span><span class="token number">0</span> <span class="token operator">&</span> s2<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span> count_if<span class="token punctuation">(</span>s1<span class="token operator">=</span><span class="token number">1</span> <span class="token operator">&</span> s2<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>db<span class="token punctuation">.</span>d1 |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>输出:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+--------------------------------------------------+--------------------------------------------------+ |
| |count_if(root.db.d1.s1 = 0 & root.db.d1.s2 = 0, 3)|count_if(root.db.d1.s1 = 1 & root.db.d1.s2 = 0, 3)| |
| +--------------------------------------------------+--------------------------------------------------+ |
| | 2| 1| |
| +--------------------------------------------------+-------------------------------------------------- |
| </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><h5 id="使用ignorenull参数" tabindex="-1"><a class="header-anchor" href="#使用ignorenull参数" aria-hidden="true">#</a> 使用ignoreNull参数</h5><p>SQL:</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> count_if<span class="token punctuation">(</span>s1<span class="token operator">=</span><span class="token number">0</span> <span class="token operator">&</span> s2<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token string">'ignoreNull'</span><span class="token operator">=</span><span class="token string">'false'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> count_if<span class="token punctuation">(</span>s1<span class="token operator">=</span><span class="token number">1</span> <span class="token operator">&</span> s2<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token string">'ignoreNull'</span><span class="token operator">=</span><span class="token string">'false'</span><span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>db<span class="token punctuation">.</span>d1 |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>输出:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+------------------------------------------------------------------------+------------------------------------------------------------------------+ |
| |count_if(root.db.d1.s1 = 0 & root.db.d1.s2 = 0, 3, "ignoreNull"="false")|count_if(root.db.d1.s1 = 1 & root.db.d1.s2 = 0, 3, "ignoreNull"="false")| |
| +------------------------------------------------------------------------+------------------------------------------------------------------------+ |
| | 1| 1| |
| +------------------------------------------------------------------------+------------------------------------------------------------------------+ |
| </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>`,24);function i(r,l){return s(),a("div",null,[e(` |
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| "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
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| `),o])}const c=n(d,[["render",i],["__file","Aggregation.html.vue"]]);export{c as default}; |
