<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 10. Type Conversion</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="functions-event-triggers.html" title="9.28. Event Trigger Functions" /><link rel="next" href="typeconv-overview.html" title="10.1. Overview" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 10. Type Conversion</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="functions-event-triggers.html" title="9.28. Event Trigger Functions">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql.html" title="Part II. The SQL Language">Up</a></td><th width="60%" align="center">Part II. The SQL Language</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="typeconv-overview.html" title="10.1. Overview">Next</a></td></tr></table><hr></hr></div><div class="chapter" id="TYPECONV"><div class="titlepage"><div><div><h2 class="title">Chapter 10. Type Conversion</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="typeconv-overview.html">10.1. Overview</a></span></dt><dt><span class="sect1"><a href="typeconv-oper.html">10.2. Operators</a></span></dt><dt><span class="sect1"><a href="typeconv-func.html">10.3. Functions</a></span></dt><dt><span class="sect1"><a href="typeconv-query.html">10.4. Value Storage</a></span></dt><dt><span class="sect1"><a href="typeconv-union-case.html">10.5. <code class="literal">UNION</code>, <code class="literal">CASE</code>, and Related Constructs</a></span></dt><dt><span class="sect1"><a href="typeconv-select.html">10.6. <code class="literal">SELECT</code> Output Columns</a></span></dt></dl></div><a id="id-1.5.9.2" class="indexterm"></a><p> <acronym class="acronym">SQL</acronym> statements can, intentionally or not, require the mixing of different data types in the same expression. <span class="productname">PostgreSQL</span> has extensive facilities for evaluating mixed-type expressions. </p><p> In many cases a user does not need to understand the details of the type conversion mechanism. However, implicit conversions done by <span class="productname">PostgreSQL</span> can affect the results of a query. When necessary, these results can be tailored by using <span class="emphasis"><em>explicit</em></span> type conversion. </p><p> This chapter introduces the <span class="productname">PostgreSQL</span> type conversion mechanisms and conventions. Refer to the relevant sections in <a class="xref" href="datatype.html" title="Chapter 8. Data Types">Chapter 8</a> and <a class="xref" href="functions.html" title="Chapter 9. Functions and Operators">Chapter 9</a> for more information on specific data types and allowed functions and operators. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="functions-event-triggers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="typeconv-overview.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9.28. Event Trigger Functions </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 10.1. Overview</td></tr></table></div></body></html>
