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class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Use Alias"><!---->Use Alias<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#operator" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Operator"><!---->Operator<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#function" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Function"><!---->Function<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#aggregate-functions" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="aggregate functions"><!---->aggregate functions<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#time-series-generation-function" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Time series generation function"><!---->Time series generation function<!----></a><ul class="sidebar-sub-headers"></ul></li></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Nested Expressions"><!---->Nested Expressions<!----></a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions-with-time-series-query" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Nested Expressions with Time Series Query"><!---->Nested Expressions with Time Series Query<!----></a><ul class="sidebar-sub-headers"></ul></li><li class="sidebar-sub-header"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions-query-with-aggregations" class="router-link-active router-link-exact-active nav-link sidebar-link heading" aria-label="Nested Expressions query with aggregations"><!---->Nested Expressions query with aggregations<!----></a><ul class="sidebar-sub-headers"></ul></li></ul></li></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Last-Query.html" class="nav-link sidebar-link sidebar-page" aria-label="Last Query"><!---->Last Query<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Align-By.html" class="nav-link sidebar-link sidebar-page" aria-label="Query Alignment Mode"><!---->Query Alignment Mode<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Where-Condition.html" class="nav-link sidebar-link sidebar-page" aria-label="Where Condition"><!---->Where Condition<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Group-By.html" class="nav-link sidebar-link sidebar-page" aria-label="Group By"><!---->Group By<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Having-Condition.html" class="nav-link sidebar-link sidebar-page" aria-label="Having Condition"><!---->Having Condition<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Fill.html" class="nav-link sidebar-link sidebar-page" aria-label="Fill Null Value"><!---->Fill Null Value<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Pagination.html" class="nav-link sidebar-link sidebar-page" aria-label="Pagination"><!---->Pagination<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Select-Into.html" class="nav-link sidebar-link sidebar-page" aria-label="Select Into"><!---->Select Into<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/UserGuide/V1.0.x/Query-Data/Continuous-Query.html" class="nav-link sidebar-link sidebar-page" aria-label="Continuous Query"><!---->Continuous Query<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li></ul></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Operators and Functions</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Trigger</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Monitor and Alert</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Administration Management</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Maintenance Tools</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Collaboration of Edge and Cloud</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Ecosystem Integration</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Cluster</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">FAQ</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">Reference</span><span class="arrow end"></span></button><!----></section></li></ul><!--[--><!----><!--]--></aside><!--[--><main class="page" id="main-content"><!--[--><!----><nav class="breadcrumb disable"></nav><div class="page-title"><h1><!---->Select Expression</h1><div class="page-info"><!----><!----><!----><!----><span class="page-reading-time-info" aria-label="Reading Time"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon"><path d="M799.387 122.15c4.402-2.978 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id="toc"><!--[--><!----><!--]--><div class="toc-header">On This Page<button class="print-button" title="Print"><svg xmlns="http://www.w3.org/2000/svg" class="icon print-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="print icon"><path d="M819.2 364.8h-44.8V128c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v236.8h-44.8C145.067 364.8 96 413.867 96 473.6v192c0 59.733 49.067 108.8 108.8 108.8h44.8V896c0 17.067 14.933 32 32 32h460.8c17.067 0 32-14.933 32-32V774.4h44.8c59.733 0 108.8-49.067 108.8-108.8v-192c0-59.733-49.067-108.8-108.8-108.8zM313.6 160h396.8v204.8H313.6V160zm396.8 704H313.6V620.8h396.8V864zM864 665.6c0 25.6-19.2 44.8-44.8 44.8h-44.8V588.8c0-17.067-14.933-32-32-32H281.6c-17.067 0-32 14.933-32 32v121.6h-44.8c-25.6 0-44.8-19.2-44.8-44.8v-192c0-25.6 19.2-44.8 44.8-44.8h614.4c25.6 0 44.8 19.2 44.8 44.8v192z"></path></svg></button></div><div class="toc-wrapper"><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#use-alias" class="router-link-active router-link-exact-active toc-link level2">Use Alias</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#operator" class="router-link-active router-link-exact-active toc-link level2">Operator</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#function" class="router-link-active router-link-exact-active toc-link level2">Function</a></li><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#aggregate-functions" class="router-link-active router-link-exact-active toc-link level3">aggregate functions</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#time-series-generation-function" class="router-link-active router-link-exact-active toc-link level3">Time series generation function</a></li><!----><!--]--></ul><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions" class="router-link-active router-link-exact-active toc-link level2">Nested Expressions</a></li><ul class="toc-list"><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions-with-time-series-query" class="router-link-active router-link-exact-active toc-link level3">Nested Expressions with Time Series Query</a></li><!----><!--]--><!--[--><li class="toc-item"><a aria-current="page" href="/UserGuide/V1.0.x/Query-Data/Select-Expression.html#nested-expressions-query-with-aggregations" class="router-link-active router-link-exact-active toc-link level3">Nested Expressions query with aggregations</a></li><!----><!--]--></ul><!--]--></ul></div><!--[--><!----><!--]--></aside></div><!----><div class="theme-hope-content"><!-- |
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| --><h1 id="select-expression" tabindex="-1"><a class="header-anchor" href="#select-expression" aria-hidden="true">#</a> Select Expression</h1><p>The <code>SELECT</code> clause specifies the output of the query, consisting of several <code>selectExpr</code>. Each <code>selectExpr</code> defines one or more columns in the query result.</p><p>**<code>selectExpr</code> is an expression consisting of time series path suffixes, constants, functions, and operators. That is, <code>selectExpr</code> can contain: **</p><ul><li>Time series path suffix (wildcards are supported)</li><li>operator <ul><li>Arithmetic operators</li><li>comparison operators</li><li>Logical Operators</li></ul></li><li>function <ul><li>aggregate functions</li><li>Time series generation functions (including built-in functions and user-defined functions)</li></ul></li><li>constant</li></ul><h2 id="use-alias" tabindex="-1"><a class="header-anchor" href="#use-alias" aria-hidden="true">#</a> Use Alias</h2><p>Since the unique data model of IoTDB, lots of additional information like device will be carried before each sensor. Sometimes, we want to query just one specific device, then these prefix information show frequently will be redundant in this situation, influencing the analysis of result set. At this time, we can use <code>AS</code> function provided by IoTDB, assign an alias to time series selected in query.</p><p>For example：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> s1 <span class="token keyword">as</span> temperature<span class="token punctuation">,</span> s2 <span class="token keyword">as</span> speed <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 punctuation">;</span> |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>The result set is：</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><h2 id="operator" tabindex="-1"><a class="header-anchor" href="#operator" aria-hidden="true">#</a> Operator</h2><p>See the documentation <a href="/UserGuide/V1.0.x/Operators-Functions/Overview.html" class="">Operators and Functions</a> for a list of operators supported in IoTDB.</p><h2 id="function" tabindex="-1"><a class="header-anchor" href="#function" aria-hidden="true">#</a> Function</h2><h3 id="aggregate-functions" tabindex="-1"><a class="header-anchor" href="#aggregate-functions" aria-hidden="true">#</a> aggregate functions</h3><p>Aggregate functions are many-to-one functions. They perform aggregate calculations on a set of values, resulting in a single aggregated result.</p><p><strong>A query that contains an aggregate function is called an aggregate query</strong>, otherwise, it is called a time series query.</p><blockquote><p>Please note that mixed use of <code>Aggregate Query</code> and <code>Timeseries Query</code> is not allowed. Below are examples for queries that are not allowed.</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>select a, count(a) from root.sg |
| select sin(a), count(a) from root.sg |
| select a, count(a) from root.sg group by ([10,100),10ms) |
| </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></div></blockquote><p>For the aggregation functions supported by IoTDB, see the document <a href="/UserGuide/V1.0.x/Operators-Functions/Aggregation.html" class="">Aggregation Functions</a>.</p><h3 id="time-series-generation-function" tabindex="-1"><a class="header-anchor" href="#time-series-generation-function" aria-hidden="true">#</a> Time series generation function</h3><p>A time series generation function takes several raw time series as input and produces a list of time series as output. Unlike aggregate functions, time series generators have a timestamp column in their result sets.</p><p>All time series generation functions accept * as input, and all can be mixed with raw time series queries.</p><h4 id="built-in-time-series-generation-functions" tabindex="-1"><a class="header-anchor" href="#built-in-time-series-generation-functions" aria-hidden="true">#</a> Built-in time series generation functions</h4><p>See the documentation <a href="/UserGuide/V1.0.x/Operators-Functions/Overview.html" class="">Operators and Functions</a> for a list of built-in functions supported in IoTDB.</p><h4 id="user-defined-time-series-generation-function" tabindex="-1"><a class="header-anchor" href="#user-defined-time-series-generation-function" aria-hidden="true">#</a> User-Defined time series generation function</h4><p>IoTDB supports function extension through User Defined Function (click for <a href="/UserGuide/V1.0.x/Operators-Functions/User-Defined-Function.html" class="">User-Defined Function</a>) capability.</p><h2 id="nested-expressions" tabindex="-1"><a class="header-anchor" href="#nested-expressions" aria-hidden="true">#</a> Nested Expressions</h2><p>IoTDB supports the calculation of arbitrary nested expressions. Since time series query and aggregation query can not be used in a query statement at the same time, we divide nested expressions into two types, which are nested expressions with time series query and nested expressions with aggregation query.</p><p>The following is the syntax definition of the <code>select</code> clause:</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code>selectClause |
| : <span class="token keyword">SELECT</span> resultColumn <span class="token punctuation">(</span><span class="token string">','</span> resultColumn<span class="token punctuation">)</span><span class="token operator">*</span> |
| <span class="token punctuation">;</span> |
| |
| resultColumn |
| : expression <span class="token punctuation">(</span><span class="token keyword">AS</span> ID<span class="token punctuation">)</span>? |
| <span class="token punctuation">;</span> |
| |
| expression |
| : <span class="token string">'('</span> expression <span class="token string">')'</span> |
| <span class="token operator">|</span> <span class="token string">'-'</span> expression |
| <span class="token operator">|</span> expression <span class="token punctuation">(</span><span class="token string">'*'</span> <span class="token operator">|</span> <span class="token string">'/'</span> <span class="token operator">|</span> <span class="token string">'%'</span><span class="token punctuation">)</span> expression |
| <span class="token operator">|</span> expression <span class="token punctuation">(</span><span class="token string">'+'</span> <span class="token operator">|</span> <span class="token string">'-'</span><span class="token punctuation">)</span> expression |
| <span class="token operator">|</span> functionName <span class="token string">'('</span> expression <span class="token punctuation">(</span><span class="token string">','</span> expression<span class="token punctuation">)</span><span class="token operator">*</span> functionAttribute<span class="token operator">*</span> <span class="token string">')'</span> |
| <span class="token operator">|</span> timeSeriesSuffixPath |
| <span class="token operator">|</span> number |
| <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 class="line-number"></div><div class="line-number"></div></div></div><h3 id="nested-expressions-with-time-series-query" tabindex="-1"><a class="header-anchor" href="#nested-expressions-with-time-series-query" aria-hidden="true">#</a> Nested Expressions with Time Series Query</h3><p>IoTDB supports the calculation of arbitrary nested expressions consisting of <strong>numbers, time series, time series generating functions (including user-defined functions) and arithmetic expressions</strong> in the <code>select</code> clause.</p><h5 id="example" tabindex="-1"><a class="header-anchor" href="#example" aria-hidden="true">#</a> Example</h5><p>Input1：</p><div class="language-sql line-numbers-mode" data-ext="sql"><pre class="language-sql"><code><span class="token keyword">select</span> a<span class="token punctuation">,</span> |
| b<span class="token punctuation">,</span> |
| <span class="token punctuation">(</span><span class="token punctuation">(</span>a <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">+</span> <span class="token number">1.5</span><span class="token punctuation">,</span> |
| sin<span class="token punctuation">(</span>a <span class="token operator">+</span> sin<span class="token punctuation">(</span>a <span class="token operator">+</span> sin<span class="token punctuation">(</span>b<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><span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token punctuation">(</span>sin<span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">*</span> sin<span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">+</span> cos<span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">*</span> cos<span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span> |
| <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg1<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></div><p>Result1：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+----------+----------+----------------------------------------+---------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+ |
| | Time|root.sg1.a|root.sg1.b|((((root.sg1.a + 1) * 2) - 1) % 2) + 1.5|sin(root.sg1.a + sin(root.sg1.a + sin(root.sg1.b)))|(-root.sg1.a + root.sg1.b * ((sin(root.sg1.a + root.sg1.b) * sin(root.sg1.a + root.sg1.b)) + (cos(root.sg1.a + root.sg1.b) * cos(root.sg1.a + root.sg1.b)))) + 1| |
| +-----------------------------+----------+----------+----------------------------------------+---------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+ |
| |1970-01-01T08:00:00.010+08:00| 1| 1| 2.5| 0.9238430524420609| -1.0| |
| |1970-01-01T08:00:00.020+08:00| 2| 2| 2.5| 0.7903505371876317| -3.0| |
| |1970-01-01T08:00:00.030+08:00| 3| 3| 2.5| 0.14065207680386618| -5.0| |
| |1970-01-01T08:00:00.040+08:00| 4| null| 2.5| null| null| |
| |1970-01-01T08:00:00.050+08:00| null| 5| null| null| null| |
| |1970-01-01T08:00:00.060+08:00| 6| 6| 2.5| -0.7288037411970916| -11.0| |
| +-----------------------------+----------+----------+----------------------------------------+---------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------+ |
| Total line number = 6 |
| It costs 0.048s |
| </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><p>Input2：</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 punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">2</span> <span class="token operator">+</span> sin<span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>Result2：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+----------------------------------------------+ |
| | Time|((root.sg.a + root.sg.b) * 2) + sin(root.sg.a)| |
| +-----------------------------+----------------------------------------------+ |
| |1970-01-01T08:00:00.010+08:00| 59.45597888911063| |
| |1970-01-01T08:00:00.020+08:00| 100.91294525072763| |
| |1970-01-01T08:00:00.030+08:00| 139.01196837590714| |
| |1970-01-01T08:00:00.040+08:00| 180.74511316047935| |
| |1970-01-01T08:00:00.050+08:00| 219.73762514629607| |
| |1970-01-01T08:00:00.060+08:00| 259.6951893788978| |
| |1970-01-01T08:00:00.070+08:00| 300.7738906815579| |
| |1970-01-01T08:00:00.090+08:00| 39.45597888911063| |
| |1970-01-01T08:00:00.100+08:00| 39.45597888911063| |
| +-----------------------------+----------------------------------------------+ |
| Total line number = 9 |
| It costs 0.011s |
| </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><p>Input3：</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 punctuation">(</span>a <span class="token operator">+</span> <span class="token operator">*</span><span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token number">2</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg1 |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>Result3：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+-----------------------------+-----------------------------+ |
| | Time|(root.sg1.a + root.sg1.a) / 2|(root.sg1.a + root.sg1.b) / 2| |
| +-----------------------------+-----------------------------+-----------------------------+ |
| |1970-01-01T08:00:00.010+08:00| 1.0| 1.0| |
| |1970-01-01T08:00:00.020+08:00| 2.0| 2.0| |
| |1970-01-01T08:00:00.030+08:00| 3.0| 3.0| |
| |1970-01-01T08:00:00.040+08:00| 4.0| null| |
| |1970-01-01T08:00:00.060+08:00| 6.0| 6.0| |
| +-----------------------------+-----------------------------+-----------------------------+ |
| Total line number = 5 |
| It costs 0.011s |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Input4：</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 punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">3</span> <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg<span class="token punctuation">,</span> root<span class="token punctuation">.</span>ln |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>Result4：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+---------------------------+---------------------------+---------------------------+---------------------------+ |
| | Time|(root.sg.a + root.sg.b) * 3|(root.sg.a + root.ln.b) * 3|(root.ln.a + root.sg.b) * 3|(root.ln.a + root.ln.b) * 3| |
| +-----------------------------+---------------------------+---------------------------+---------------------------+---------------------------+ |
| |1970-01-01T08:00:00.010+08:00| 90.0| 270.0| 360.0| 540.0| |
| |1970-01-01T08:00:00.020+08:00| 150.0| 330.0| 690.0| 870.0| |
| |1970-01-01T08:00:00.030+08:00| 210.0| 450.0| 570.0| 810.0| |
| |1970-01-01T08:00:00.040+08:00| 270.0| 240.0| 690.0| 660.0| |
| |1970-01-01T08:00:00.050+08:00| 330.0| null| null| null| |
| |1970-01-01T08:00:00.060+08:00| 390.0| null| null| null| |
| |1970-01-01T08:00:00.070+08:00| 450.0| null| null| null| |
| |1970-01-01T08:00:00.090+08:00| 60.0| null| null| null| |
| |1970-01-01T08:00:00.100+08:00| 60.0| null| null| null| |
| +-----------------------------+---------------------------+---------------------------+---------------------------+---------------------------+ |
| 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><h5 id="explanation" tabindex="-1"><a class="header-anchor" href="#explanation" aria-hidden="true">#</a> Explanation</h5><ul><li>Only when the left operand and the right operand under a certain timestamp are not <code>null</code>, the nested expressions will have an output value. Otherwise this row will not be included in the result. <ul><li>In Result1 of the Example part, the value of time series <code>root.sg.a</code> at time 40 is 4, while the value of time series <code>root.sg.b</code> is <code>null</code>. So at time 40, the value of nested expressions <code>(a + b) * 2 + sin(a)</code> is <code>null</code>. So in Result2, this row is not included in the result.</li></ul></li><li>If one operand in the nested expressions can be translated into multiple time series (For example, <code>*</code>), the result of each time series will be included in the result (Cartesian product). Please refer to Input3, Input4 and corresponding Result3 and Result4 in Example.</li></ul><h5 id="note" tabindex="-1"><a class="header-anchor" href="#note" aria-hidden="true">#</a> Note</h5><blockquote><p>Please note that Aligned Time Series has not been supported in Nested Expressions with Time Series Query yet. An error message is expected if you use it with Aligned Time Series selected in a query statement.</p></blockquote><h3 id="nested-expressions-query-with-aggregations" tabindex="-1"><a class="header-anchor" href="#nested-expressions-query-with-aggregations" aria-hidden="true">#</a> Nested Expressions query with aggregations</h3><p>IoTDB supports the calculation of arbitrary nested expressions consisting of <strong>numbers, aggregations and arithmetic expressions</strong> in the <code>select</code> clause.</p><h5 id="example-1" tabindex="-1"><a class="header-anchor" href="#example-1" aria-hidden="true">#</a> Example</h5><p>Aggregation query without <code>GROUP BY</code>.</p><p>Input1:</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 function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span><span class="token punctuation">,</span> |
| sin<span class="token punctuation">(</span><span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">,</span> |
| <span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> |
| <span class="token operator">-</span><span class="token function">sum</span><span class="token punctuation">(</span>hardware<span class="token punctuation">)</span><span class="token punctuation">,</span> |
| <span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token function">sum</span><span class="token punctuation">(</span>hardware<span class="token punctuation">)</span> |
| <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 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></div><p>Result1:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+--------------------------------------------------------------------+ |
| |avg(root.ln.wf01.wt01.temperature)|sin(avg(root.ln.wf01.wt01.temperature))|avg(root.ln.wf01.wt01.temperature) + 1|-sum(root.ln.wf01.wt01.hardware)|avg(root.ln.wf01.wt01.temperature) + sum(root.ln.wf01.wt01.hardware)| |
| +----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+--------------------------------------------------------------------+ |
| | 15.927999999999999| -0.21826546964855045| 16.927999999999997| -7426.0| 7441.928| |
| +----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+--------------------------------------------------------------------+ |
| Total line number = 1 |
| It costs 0.009s |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Input2:</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 function">avg</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span><span class="token punctuation">,</span> |
| <span class="token punctuation">(</span><span class="token function">avg</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">3</span> <span class="token operator">/</span> <span class="token number">2</span> <span class="token operator">-</span><span class="token number">1</span> |
| <span class="token keyword">from</span> root<span class="token punctuation">.</span>sg1 |
| </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></div><p>Result2:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+---------------+---------------+-------------------------------------+-------------------------------------+ |
| |avg(root.sg1.a)|avg(root.sg1.b)|(avg(root.sg1.a) + 1) * 3 / 2 - 1 |(avg(root.sg1.b) + 1) * 3 / 2 - 1 | |
| +---------------+---------------+-------------------------------------+-------------------------------------+ |
| | 3.2| 3.4| 5.300000000000001| 5.6000000000000005| |
| +---------------+---------------+-------------------------------------+-------------------------------------+ |
| Total line number = 1 |
| It costs 0.007s |
| </code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>Aggregation with <code>GROUP BY</code>.</p><p>Input3:</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 function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span><span class="token punctuation">,</span> |
| sin<span class="token punctuation">(</span><span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">,</span> |
| <span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> |
| <span class="token operator">-</span><span class="token function">sum</span><span class="token punctuation">(</span>hardware<span class="token punctuation">)</span><span class="token punctuation">,</span> |
| <span class="token function">avg</span><span class="token punctuation">(</span>temperature<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token function">sum</span><span class="token punctuation">(</span>hardware<span class="token punctuation">)</span> <span class="token keyword">as</span> custom_sum |
| <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">GROUP</span> <span class="token keyword">BY</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">90</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">10</span>ms<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 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><p>Result3:</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>+-----------------------------+----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+----------+ |
| | Time|avg(root.ln.wf01.wt01.temperature)|sin(avg(root.ln.wf01.wt01.temperature))|avg(root.ln.wf01.wt01.temperature) + 1|-sum(root.ln.wf01.wt01.hardware)|custom_sum| |
| +-----------------------------+----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+----------+ |
| |1970-01-01T08:00:00.010+08:00| 13.987499999999999| 0.9888207947857667| 14.987499999999999| -3211.0| 3224.9875| |
| |1970-01-01T08:00:00.020+08:00| 29.6| -0.9701057337071853| 30.6| -3720.0| 3749.6| |
| |1970-01-01T08:00:00.030+08:00| null| null| null| null| null| |
| |1970-01-01T08:00:00.040+08:00| null| null| null| null| null| |
| |1970-01-01T08:00:00.050+08:00| null| null| null| null| null| |
| |1970-01-01T08:00:00.060+08:00| null| null| null| null| null| |
| |1970-01-01T08:00:00.070+08:00| null| null| null| null| null| |
| |1970-01-01T08:00:00.080+08:00| null| null| null| null| null| |
| +-----------------------------+----------------------------------+---------------------------------------+--------------------------------------+--------------------------------+----------+ |
| Total line number = 8 |
| 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 class="line-number"></div><div class="line-number"></div></div></div><h5 id="explanation-1" tabindex="-1"><a class="header-anchor" href="#explanation-1" aria-hidden="true">#</a> Explanation</h5><ul><li>Only when the left operand and the right operand under a certain timestamp are not <code>null</code>, the nested expressions will have an output value. Otherwise this row will not be included in the result. But for nested expressions with <code>GROUP BY</code> clause, it is better to show the result of all time intervals. Please refer to Input3 and corresponding Result3 in Example.</li><li>If one operand in the nested expressions can be translated into multiple time series (For example, <code>*</code>), the result of each time series will be included in the result (Cartesian product). Please refer to Input2 and corresponding Result2 in Example.</li></ul></div><!----><footer class="page-meta"><div class="meta-item edit-link"><a href="https://github.com/apache/iotdb/edit/rel/1.0/docs/UserGuide/Query-Data/Select-Expression.md" rel="noopener noreferrer" target="_blank" aria-label="Found Error? Edit this page on GitHub" class="nav-link label"><!--[--><svg xmlns="http://www.w3.org/2000/svg" class="icon edit-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="edit icon"><path d="M430.818 653.65a60.46 60.46 0 0 1-50.96-93.281l71.69-114.012 7.773-10.365L816.038 80.138A60.46 60.46 0 0 1 859.225 62a60.46 60.46 0 0 1 43.186 18.138l43.186 43.186a60.46 60.46 0 0 1 0 86.373L588.879 565.55l-8.637 8.637-117.466 68.234a60.46 60.46 0 0 1-31.958 11.229z"></path><path d="M728.802 962H252.891A190.883 190.883 0 0 1 62.008 771.98V296.934a190.883 190.883 0 0 1 190.883-192.61h267.754a60.46 60.46 0 0 1 0 120.92H252.891a69.962 69.962 0 0 0-69.098 69.099V771.98a69.962 69.962 0 0 0 69.098 69.098h475.911A69.962 69.962 0 0 0 797.9 771.98V503.363a60.46 60.46 0 1 1 120.922 0V771.98A190.883 190.883 0 0 1 728.802 962z"></path></svg><!--]-->Found Error? Edit this page on GitHub<span><svg class="external-link-icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg><span class="external-link-icon-sr-only">open in new window</span></span><!----></a></div><div class="meta-item git-info"><!----><!----></div></footer><nav class="page-nav"><a href="/UserGuide/V1.0.x/Query-Data/Overview.html" class="nav-link prev" aria-label="Overview"><div class="hint"><span class="arrow start"></span>Prev</div><div class="link"><!---->Overview</div></a><a href="/UserGuide/V1.0.x/Query-Data/Last-Query.html" class="nav-link next" aria-label="Last Query"><div class="hint">Next<span class="arrow end"></span></div><div class="link">Last Query<!----></div></a></nav><!----><!----><!--]--></main><!--]--><footer style="padding-bottom:2rem;"><span id="doc-version" style="display:none;">rel/1.0</span><p style="text-align:center;color:#909399;font-size:12px;margin:0 30px;">Copyright © 2023 The Apache Software Foundation.<br> Apache and the Apache feather logo are trademarks of The Apache Software Foundation</p><p style="text-align:center;margin-top:10px;color:#909399;font-size:12px;margin:0 30px;"><strong>Have a question?</strong> Connect with us on QQ, WeChat, or Slack. <a href="https://github.com/apache/iotdb/issues/1995">Join the community</a> now.</p><p style="text-align:center;margin-top:10px;color:#909399;font-size:12px;margin:0 30px;"> We use <a href="https://analytics.google.com">Google Analytics</a> to collect anonymous, aggregated usage information. </p></footer></div><!--]--><!--]--><!----><!--]--></div> |
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