<?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 39. Triggers</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="extend-pgxs.html" title="38.17. Extension Building Infrastructure" /><link rel="next" href="trigger-definition.html" title="39.1. Overview of Trigger Behavior" /></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 39. Triggers</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="extend-pgxs.html" title="38.17. Extension Building Infrastructure">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="server-programming.html" title="Part V. Server Programming">Up</a></td><th width="60%" align="center">Part V. Server Programming</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="trigger-definition.html" title="39.1. Overview of Trigger Behavior">Next</a></td></tr></table><hr></hr></div><div class="chapter" id="TRIGGERS"><div class="titlepage"><div><div><h2 class="title">Chapter 39. Triggers</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="trigger-definition.html">39.1. Overview of Trigger Behavior</a></span></dt><dt><span class="sect1"><a href="trigger-datachanges.html">39.2. Visibility of Data Changes</a></span></dt><dt><span class="sect1"><a href="trigger-interface.html">39.3. Writing Trigger Functions in C</a></span></dt><dt><span class="sect1"><a href="trigger-example.html">39.4. A Complete Trigger Example</a></span></dt></dl></div><a id="id-1.8.4.2" class="indexterm"></a><p> This chapter provides general information about writing trigger functions. Trigger functions can be written in most of the available procedural languages, including <span class="application">PL/pgSQL</span> (<a class="xref" href="plpgsql.html" title="Chapter 43. PL/pgSQL - SQL Procedural Language">Chapter 43</a>), <span class="application">PL/Tcl</span> (<a class="xref" href="pltcl.html" title="Chapter 44. PL/Tcl - Tcl Procedural Language">Chapter 44</a>), <span class="application">PL/Perl</span> (<a class="xref" href="plperl.html" title="Chapter 45. PL/Perl - Perl Procedural Language">Chapter 45</a>), and <span class="application">PL/Python</span> (<a class="xref" href="plpython.html" title="Chapter 46. PL/Python - Python Procedural Language">Chapter 46</a>). After reading this chapter, you should consult the chapter for your favorite procedural language to find out the language-specific details of writing a trigger in it. </p><p> It is also possible to write a trigger function in C, although most people find it easier to use one of the procedural languages. It is not currently possible to write a trigger function in the plain SQL function language. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="extend-pgxs.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="server-programming.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="trigger-definition.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">38.17. Extension Building Infrastructure </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 39.1. Overview of Trigger Behavior</td></tr></table></div></body></html>
