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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!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>37.32. key_column_usage</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="infoschema-foreign-tables.html" title="37.31. foreign_tables" /><link rel="next" href="infoschema-parameters.html" title="37.33. parameters" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">37.32. <code class="literal">key_column_usage</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="infoschema-foreign-tables.html" title="37.31. foreign_tables">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="information-schema.html" title="Chapter 37. The Information Schema">Up</a></td><th width="60%" align="center">Chapter 37. The Information Schema</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="infoschema-parameters.html" title="37.33. parameters">Next</a></td></tr></table><hr /></div><div class="sect1" id="INFOSCHEMA-KEY-COLUMN-USAGE"><div class="titlepage"><div><div><h2 class="title" style="clear: both">37.32. <code class="literal">key_column_usage</code> <a href="#INFOSCHEMA-KEY-COLUMN-USAGE" class="id_link">#</a></h2></div></div></div><p>3   The view <code class="literal">key_column_usage</code> identifies all columns4   in the current database that are restricted by some unique, primary5   key, or foreign key constraint.  Check constraints are not included6   in this view.  Only those columns are shown that the current user7   has access to, by way of being the owner or having some privilege.8  </p><div class="table" id="id-1.7.6.36.3"><p class="title"><strong>Table 37.30. <code class="structname">key_column_usage</code> Columns</strong></p><div class="table-contents"><table class="table" summary="key_column_usage Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">9       Column Type10      </p>11      <p>12       Description13      </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">14       <code class="structfield">constraint_catalog</code> <code class="type">sql_identifier</code>15      </p>16      <p>17       Name of the database that contains the constraint (always the current database)18      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">19       <code class="structfield">constraint_schema</code> <code class="type">sql_identifier</code>20      </p>21      <p>22       Name of the schema that contains the constraint23      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">24       <code class="structfield">constraint_name</code> <code class="type">sql_identifier</code>25      </p>26      <p>27       Name of the constraint28      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">29       <code class="structfield">table_catalog</code> <code class="type">sql_identifier</code>30      </p>31      <p>32       Name of the database that contains the table that contains the33       column that is restricted by this constraint (always the34       current database)35      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">36       <code class="structfield">table_schema</code> <code class="type">sql_identifier</code>37      </p>38      <p>39       Name of the schema that contains the table that contains the40       column that is restricted by this constraint41      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">42       <code class="structfield">table_name</code> <code class="type">sql_identifier</code>43      </p>44      <p>45       Name of the table that contains the column that is restricted46       by this constraint47      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">48       <code class="structfield">column_name</code> <code class="type">sql_identifier</code>49      </p>50      <p>51       Name of the column that is restricted by this constraint52      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">53       <code class="structfield">ordinal_position</code> <code class="type">cardinal_number</code>54      </p>55      <p>56       Ordinal position of the column within the constraint key (count57       starts at 1)58      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">59       <code class="structfield">position_in_unique_constraint</code> <code class="type">cardinal_number</code>60      </p>61      <p>62       For a foreign-key constraint, ordinal position of the referenced63       column within its unique constraint (count starts at 1);64       otherwise null65      </p></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="infoschema-foreign-tables.html" title="37.31. foreign_tables">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="information-schema.html" title="Chapter 37. The Information Schema">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="infoschema-parameters.html" title="37.33. parameters">Next</a></td></tr><tr><td width="40%" align="left" valign="top">37.31. <code class="literal">foreign_tables</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 37.33. <code class="literal">parameters</code></td></tr></table></div></body></html>