Google Git
Sign in
apache / spark-website / 2c562896505588421cce257d111c8ba3805528c2 / . / site / docs / 3.4.3 / sql-ref-syntax-qry-select-case.html
blob: 9ea58a8b711e328bf5466efb168c519322a896a4 [file] [log] [blame]
<!DOCTYPE html>
<!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]> <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]> <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]-->
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>CASE Clause - Spark 3.4.3 Documentation</title>
<link rel="stylesheet" href="css/bootstrap.min.css">
<style>
body {
padding-top: 60px;
padding-bottom: 40px;
}
</style>
<meta name="viewport" content="width=device-width">
<link rel="stylesheet" href="css/main.css">
<script src="js/vendor/modernizr-2.6.1-respond-1.1.0.min.js"></script>
<link rel="stylesheet" href="css/pygments-default.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/docsearch.js@2/dist/cdn/docsearch.min.css" />
<link rel="stylesheet" href="css/docsearch.css">
<!-- Matomo -->
<script>
var _paq = window._paq = window._paq || [];
/* tracker methods like "setCustomDimension" should be called before "trackPageView" */
_paq.push(["disableCookies"]);
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
(function() {
var u="https://analytics.apache.org/";
_paq.push(['setTrackerUrl', u+'matomo.php']);
_paq.push(['setSiteId', '40']);
var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
g.async=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s);
})();
</script>
<!-- End Matomo Code -->
</head>
<body>
<!--[if lt IE 7]>
<p class="chromeframe">You are using an outdated browser. <a href="https://browsehappy.com/">Upgrade your browser today</a> or <a href="http://www.google.com/chromeframe/?redirect=true">install Google Chrome Frame</a> to better experience this site.</p>
<![endif]-->
<!-- This code is taken from http://twitter.github.com/bootstrap/examples/hero.html -->
<nav class="navbar fixed-top navbar-expand-md navbar-light bg-light" id="topbar">
<div class="container">
<div class="navbar-header">
<div class="navbar-brand"><a href="index.html">
<img src="img/spark-logo-hd.png" style="height:50px;"/></a><span class="version">3.4.3</span>
</div>
</div>
<button class="navbar-toggler" type="button" data-toggle="collapse"
data-target="#navbarCollapse" aria-controls="navbarCollapse"
aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarCollapse">
<ul class="navbar-nav">
<!--TODO(andyk): Add class="active" attribute to li some how.-->
<li class="nav-item"><a href="index.html" class="nav-link">Overview</a></li>
<li class="nav-item dropdown">
<a href="#" class="nav-link dropdown-toggle" id="navbarQuickStart" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Programming Guides</a>
<div class="dropdown-menu" aria-labelledby="navbarQuickStart">
<a class="dropdown-item" href="quick-start.html">Quick Start</a>
<a class="dropdown-item" href="rdd-programming-guide.html">RDDs, Accumulators, Broadcasts Vars</a>
<a class="dropdown-item" href="sql-programming-guide.html">SQL, DataFrames, and Datasets</a>
<a class="dropdown-item" href="structured-streaming-programming-guide.html">Structured Streaming</a>
<a class="dropdown-item" href="streaming-programming-guide.html">Spark Streaming (DStreams)</a>
<a class="dropdown-item" href="ml-guide.html">MLlib (Machine Learning)</a>
<a class="dropdown-item" href="graphx-programming-guide.html">GraphX (Graph Processing)</a>
<a class="dropdown-item" href="sparkr.html">SparkR (R on Spark)</a>
<a class="dropdown-item" href="api/python/getting_started/index.html">PySpark (Python on Spark)</a>
</div>
</li>
<li class="nav-item dropdown">
<a href="#" class="nav-link dropdown-toggle" id="navbarAPIDocs" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">API Docs</a>
<div class="dropdown-menu" aria-labelledby="navbarAPIDocs">
<a class="dropdown-item" href="api/scala/org/apache/spark/index.html">Scala</a>
<a class="dropdown-item" href="api/java/index.html">Java</a>
<a class="dropdown-item" href="api/python/index.html">Python</a>
<a class="dropdown-item" href="api/R/index.html">R</a>
<a class="dropdown-item" href="api/sql/index.html">SQL, Built-in Functions</a>
</div>
</li>
<li class="nav-item dropdown">
<a href="#" class="nav-link dropdown-toggle" id="navbarDeploying" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Deploying</a>
<div class="dropdown-menu" aria-labelledby="navbarDeploying">
<a class="dropdown-item" href="cluster-overview.html">Overview</a>
<a class="dropdown-item" href="submitting-applications.html">Submitting Applications</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="spark-standalone.html">Spark Standalone</a>
<a class="dropdown-item" href="running-on-mesos.html">Mesos</a>
<a class="dropdown-item" href="running-on-yarn.html">YARN</a>
<a class="dropdown-item" href="running-on-kubernetes.html">Kubernetes</a>
</div>
</li>
<li class="nav-item dropdown">
<a href="#" class="nav-link dropdown-toggle" id="navbarMore" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">More</a>
<div class="dropdown-menu" aria-labelledby="navbarMore">
<a class="dropdown-item" href="configuration.html">Configuration</a>
<a class="dropdown-item" href="monitoring.html">Monitoring</a>
<a class="dropdown-item" href="tuning.html">Tuning Guide</a>
<a class="dropdown-item" href="job-scheduling.html">Job Scheduling</a>
<a class="dropdown-item" href="security.html">Security</a>
<a class="dropdown-item" href="hardware-provisioning.html">Hardware Provisioning</a>
<a class="dropdown-item" href="migration-guide.html">Migration Guide</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="building-spark.html">Building Spark</a>
<a class="dropdown-item" href="https://spark.apache.org/contributing.html">Contributing to Spark</a>
<a class="dropdown-item" href="https://spark.apache.org/third-party-projects.html">Third Party Projects</a>
</div>
</li>
<li class="nav-item">
<input type="text" id="docsearch-input" placeholder="Search the docs…">
</li>
</ul>
<!--<span class="navbar-text navbar-right"><span class="version-text">v3.4.3</span></span>-->
</div>
</div>
</nav>
<div class="container-wrapper">
<div class="left-menu-wrapper">
<div class="left-menu">
<h3><a href="sql-programming-guide.html">Spark SQL Guide</a></h3>
<ul>
<li>
<a href="sql-getting-started.html">
Getting Started
</a>
</li>
<li>
<a href="sql-data-sources.html">
Data Sources
</a>
</li>
<li>
<a href="sql-performance-tuning.html">
Performance Tuning
</a>
</li>
<li>
<a href="sql-distributed-sql-engine.html">
Distributed SQL Engine
</a>
</li>
<li>
<a href="sql-pyspark-pandas-with-arrow.html">
PySpark Usage Guide for Pandas with Apache Arrow
</a>
</li>
<li>
<a href="sql-migration-old.html">
Migration Guide
</a>
</li>
<li>
<a href="sql-ref.html">
SQL Reference
</a>
</li>
<ul>
<li>
<a href="sql-ref-ansi-compliance.html">
ANSI Compliance
</a>
</li>
<li>
<a href="sql-ref-datatypes.html">
Data Types
</a>
</li>
<li>
<a href="sql-ref-datetime-pattern.html">
Datetime Pattern
</a>
</li>
<li>
<a href="sql-ref-number-pattern.html">
Number Pattern
</a>
</li>
<li>
<a href="sql-ref-functions.html">
Functions
</a>
</li>
<li>
<a href="sql-ref-identifier.html">
Identifiers
</a>
</li>
<li>
<a href="sql-ref-literals.html">
Literals
</a>
</li>
<li>
<a href="sql-ref-null-semantics.html">
Null Semantics
</a>
</li>
<li>
<a href="sql-ref-syntax.html">
SQL Syntax
</a>
</li>
<ul>
<li>
<a href="sql-ref-syntax.html#ddl-statements">
Data Definition Statements
</a>
</li>
<li>
<a href="sql-ref-syntax.html#dml-statements">
Data Manipulation Statements
</a>
</li>
<li>
<a href="sql-ref-syntax.html#data-retrieval-statements">
Data Retrieval(Queries)
</a>
</li>
<li>
<a href="sql-ref-syntax.html#auxiliary-statements">
Auxiliary Statements
</a>
</li>
</ul>
</ul>
<li>
<a href="sql-error-conditions.html">
Error Conditions
</a>
</li>
</ul>
</div>
</div>
<input id="nav-trigger" class="nav-trigger" checked type="checkbox">
<label for="nav-trigger"></label>
<div class="content-with-sidebar mr-3" id="content">
<h1 class="title">CASE Clause</h1>
<h3 id="description">Description</h3>
<p><code class="language-plaintext highlighter-rouge">CASE</code> clause uses a rule to return a specific result based on the specified condition, similar to if/else statements in other programming languages.</p>
<h3 id="syntax">Syntax</h3>
<div class="language-sql highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">CASE</span> <span class="p">[</span> <span class="n">expression</span> <span class="p">]</span> <span class="err">{</span> <span class="k">WHEN</span> <span class="n">boolean_expression</span> <span class="k">THEN</span> <span class="n">then_expression</span> <span class="err">}</span> <span class="p">[</span> <span class="p">...</span> <span class="p">]</span>
<span class="p">[</span> <span class="k">ELSE</span> <span class="n">else_expression</span> <span class="p">]</span>
<span class="k">END</span>
</code></pre></div></div>
<h3 id="parameters">Parameters</h3>
<ul>
<li>
<p><strong>boolean_expression</strong></p>
<p>Specifies any expression that evaluates to a result type <code class="language-plaintext highlighter-rouge">boolean</code>. Two or
more expressions may be combined together using the logical
operators ( <code class="language-plaintext highlighter-rouge">AND</code>, <code class="language-plaintext highlighter-rouge">OR</code> ).</p>
</li>
<li>
<p><strong>then_expression</strong></p>
<p>Specifies the then expression based on the <code class="language-plaintext highlighter-rouge">boolean_expression</code> condition; <code class="language-plaintext highlighter-rouge">then_expression</code> and <code class="language-plaintext highlighter-rouge">else_expression</code> should all be same type or coercible to a common type.</p>
</li>
<li>
<p><strong>else_expression</strong></p>
<p>Specifies the default expression; <code class="language-plaintext highlighter-rouge">then_expression</code> and <code class="language-plaintext highlighter-rouge">else_expression</code> should all be same type or coercible to a common type.</p>
</li>
</ul>
<h3 id="examples">Examples</h3>
<div class="language-sql highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">CREATE</span> <span class="k">TABLE</span> <span class="n">person</span> <span class="p">(</span><span class="n">id</span> <span class="nb">INT</span><span class="p">,</span> <span class="n">name</span> <span class="n">STRING</span><span class="p">,</span> <span class="n">age</span> <span class="nb">INT</span><span class="p">);</span>
<span class="k">INSERT</span> <span class="k">INTO</span> <span class="n">person</span> <span class="k">VALUES</span>
<span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="s1">'John'</span><span class="p">,</span> <span class="mi">30</span><span class="p">),</span>
<span class="p">(</span><span class="mi">200</span><span class="p">,</span> <span class="s1">'Mary'</span><span class="p">,</span> <span class="k">NULL</span><span class="p">),</span>
<span class="p">(</span><span class="mi">300</span><span class="p">,</span> <span class="s1">'Mike'</span><span class="p">,</span> <span class="mi">80</span><span class="p">),</span>
<span class="p">(</span><span class="mi">400</span><span class="p">,</span> <span class="s1">'Dan'</span><span class="p">,</span> <span class="mi">50</span><span class="p">);</span>
<span class="k">SELECT</span> <span class="n">id</span><span class="p">,</span> <span class="k">CASE</span> <span class="k">WHEN</span> <span class="n">id</span> <span class="o">&gt;</span> <span class="mi">200</span> <span class="k">THEN</span> <span class="s1">'bigger'</span> <span class="k">ELSE</span> <span class="s1">'small'</span> <span class="k">END</span> <span class="k">FROM</span> <span class="n">person</span><span class="p">;</span>
<span class="o">+</span><span class="c1">------+--------------------------------------------------+</span>
<span class="o">|</span> <span class="n">id</span> <span class="o">|</span> <span class="k">CASE</span> <span class="k">WHEN</span> <span class="p">(</span><span class="n">id</span> <span class="o">&gt;</span> <span class="mi">200</span><span class="p">)</span> <span class="k">THEN</span> <span class="n">bigger</span> <span class="k">ELSE</span> <span class="n">small</span> <span class="k">END</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+--------------------------------------------------+</span>
<span class="o">|</span> <span class="mi">100</span> <span class="o">|</span> <span class="n">small</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">200</span> <span class="o">|</span> <span class="n">small</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">300</span> <span class="o">|</span> <span class="n">bigger</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">400</span> <span class="o">|</span> <span class="n">bigger</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+--------------------------------------------------+</span>
<span class="k">SELECT</span> <span class="n">id</span><span class="p">,</span> <span class="k">CASE</span> <span class="n">id</span> <span class="k">WHEN</span> <span class="mi">100</span> <span class="k">then</span> <span class="s1">'bigger'</span> <span class="k">WHEN</span> <span class="n">id</span> <span class="o">&gt;</span> <span class="mi">300</span> <span class="k">THEN</span> <span class="s1">'300'</span> <span class="k">ELSE</span> <span class="s1">'small'</span> <span class="k">END</span> <span class="k">FROM</span> <span class="n">person</span><span class="p">;</span>
<span class="o">+</span><span class="c1">------+-----------------------------------------------------------------------------------------------+</span>
<span class="o">|</span> <span class="n">id</span> <span class="o">|</span> <span class="k">CASE</span> <span class="k">WHEN</span> <span class="p">(</span><span class="n">id</span> <span class="o">=</span> <span class="mi">100</span><span class="p">)</span> <span class="k">THEN</span> <span class="n">bigger</span> <span class="k">WHEN</span> <span class="p">(</span><span class="n">id</span> <span class="o">=</span> <span class="k">CAST</span><span class="p">((</span><span class="n">id</span> <span class="o">&gt;</span> <span class="mi">300</span><span class="p">)</span> <span class="k">AS</span> <span class="nb">INT</span><span class="p">))</span> <span class="k">THEN</span> <span class="mi">300</span> <span class="k">ELSE</span> <span class="n">small</span> <span class="k">END</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+-----------------------------------------------------------------------------------------------+</span>
<span class="o">|</span> <span class="mi">100</span> <span class="o">|</span> <span class="n">bigger</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">200</span> <span class="o">|</span> <span class="n">small</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">300</span> <span class="o">|</span> <span class="n">small</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">400</span> <span class="o">|</span> <span class="n">small</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+-----------------------------------------------------------------------------------------------+</span>
<span class="k">SELECT</span> <span class="o">*</span> <span class="k">FROM</span> <span class="n">person</span>
<span class="k">WHERE</span>
<span class="k">CASE</span> <span class="mi">1</span> <span class="o">=</span> <span class="mi">1</span>
<span class="k">WHEN</span> <span class="mi">100</span> <span class="k">THEN</span> <span class="s1">'big'</span>
<span class="k">WHEN</span> <span class="mi">200</span> <span class="k">THEN</span> <span class="s1">'bigger'</span>
<span class="k">WHEN</span> <span class="mi">300</span> <span class="k">THEN</span> <span class="s1">'biggest'</span>
<span class="k">ELSE</span> <span class="s1">'small'</span>
<span class="k">END</span> <span class="o">=</span> <span class="s1">'small'</span><span class="p">;</span>
<span class="o">+</span><span class="c1">------+-------+-------+</span>
<span class="o">|</span> <span class="n">id</span> <span class="o">|</span> <span class="n">name</span> <span class="o">|</span> <span class="n">age</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+-------+-------+</span>
<span class="o">|</span> <span class="mi">100</span> <span class="o">|</span> <span class="n">John</span> <span class="o">|</span> <span class="mi">30</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">200</span> <span class="o">|</span> <span class="n">Mary</span> <span class="o">|</span> <span class="k">NULL</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">300</span> <span class="o">|</span> <span class="n">Mike</span> <span class="o">|</span> <span class="mi">80</span> <span class="o">|</span>
<span class="o">|</span> <span class="mi">400</span> <span class="o">|</span> <span class="n">Dan</span> <span class="o">|</span> <span class="mi">50</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">------+-------+-------+</span>
</code></pre></div></div>
<h3 id="related-statements">Related Statements</h3>
<ul>
<li><a href="sql-ref-syntax-qry-select.html">SELECT Main</a></li>
<li><a href="sql-ref-syntax-qry-select-where.html">WHERE Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-groupby.html">GROUP BY Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-having.html">HAVING Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-orderby.html">ORDER BY Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-sortby.html">SORT BY Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-distribute-by.html">DISTRIBUTE BY Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-limit.html">LIMIT Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-offset.html">OFFSET Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-pivot.html">PIVOT Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-unpivot.html">UNPIVOT Clause</a></li>
<li><a href="sql-ref-syntax-qry-select-lateral-view.html">LATERAL VIEW Clause</a></li>
</ul>
</div>
<!-- /container -->
</div>
<script src="js/vendor/jquery-3.5.1.min.js"></script>
<script src="js/vendor/bootstrap.bundle.min.js"></script>
<script src="js/vendor/anchor.min.js"></script>
<script src="js/main.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/docsearch.js@2/dist/cdn/docsearch.min.js"></script>
<script type="text/javascript">
// DocSearch is entirely free and automated. DocSearch is built in two parts:
// 1. a crawler which we run on our own infrastructure every 24 hours. It follows every link
// in your website and extract content from every page it traverses. It then pushes this
// content to an Algolia index.
// 2. a JavaScript snippet to be inserted in your website that will bind this Algolia index
// to your search input and display its results in a dropdown UI. If you want to find more
// details on how works DocSearch, check the docs of DocSearch.
docsearch({
apiKey: 'd62f962a82bc9abb53471cb7b89da35e',
appId: 'RAI69RXRSK',
indexName: 'apache_spark',
inputSelector: '#docsearch-input',
enhancedSearchInput: true,
algoliaOptions: {
'facetFilters': ["version:3.4.3"]
},
debug: false // Set debug to true if you want to inspect the dropdown
});
</script>
<!-- MathJax Section -->
<script type="text/x-mathjax-config">
MathJax.Hub.Config({
TeX: { equationNumbers: { autoNumber: "AMS" } }
});
</script>
<script>
// Note that we load MathJax this way to work with local file (file://), HTTP and HTTPS.
// We could use "//cdn.mathjax...", but that won't support "file://".
(function(d, script) {
script = d.createElement('script');
script.type = 'text/javascript';
script.async = true;
script.onload = function(){
MathJax.Hub.Config({
tex2jax: {
inlineMath: [ ["$", "$"], ["\\\\(","\\\\)"] ],
displayMath: [ ["$$","$$"], ["\\[", "\\]"] ],
processEscapes: true,
skipTags: ['script', 'noscript', 'style', 'textarea', 'pre']
}
});
};
script.src = ('https:' == document.location.protocol ? 'https://' : 'http://') +
'cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js' +
'?config=TeX-AMS-MML_HTMLorMML';
d.getElementsByTagName('head')[0].appendChild(script);
}(document));
</script>
</body>
</html>