<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >key_column_usage</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="The Information Schema" HREF="information-schema.html"><LINK REL="PREVIOUS" TITLE="enabled_roles" HREF="infoschema-enabled-roles.html"><LINK REL="NEXT" TITLE="parameters" HREF="infoschema-parameters.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2007-02-02T03:57:22"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="infoschema-enabled-roles.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="information-schema.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 30. The Information Schema</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="information-schema.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="infoschema-parameters.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="INFOSCHEMA-KEY-COLUMN-USAGE" >30.18. <TT CLASS="LITERAL" >key_column_usage</TT ></A ></H1 ><P > The view <TT CLASS="LITERAL" >key_column_usage</TT > identifies all columns in the current database that are restricted by some unique, primary key, or foreign key constraint. Check constraints are not included in this view. Only those columns are shown that are contained in a table owned by the current user. </P ><DIV CLASS="TABLE" ><A NAME="AEN27245" ></A ><P ><B >Table 30-16. <TT CLASS="LITERAL" >key_column_usage</TT > Columns</B ></P ><TABLE BORDER="1" CLASS="CALSTABLE" ><COL><COL><COL><THEAD ><TR ><TH >Name</TH ><TH >Data Type</TH ><TH >Description</TH ></TR ></THEAD ><TBODY ><TR ><TD ><TT CLASS="LITERAL" >constraint_catalog</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD >Name of the database that contains the constraint (always the current database)</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >constraint_schema</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD >Name of the schema that contains the constraint</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >constraint_name</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD >Name of the constraint</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >table_catalog</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD > Name of the database that contains the table that contains the column that is restricted by some constraint (always the current database) </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >table_schema</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD > Name of the schema that contains the table that contains the column that is restricted by some constraint </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >table_name</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD > Name of the table that contains the column that is restricted by some constraint </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >column_name</TT ></TD ><TD ><TT CLASS="TYPE" >sql_identifier</TT ></TD ><TD > Name of the column that is restricted by some constraint </TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >ordinal_position</TT ></TD ><TD ><TT CLASS="TYPE" >cardinal_number</TT ></TD ><TD > Ordinal position of the column within the constraint key (count starts at 1) </TD ></TR ></TBODY ></TABLE ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="infoschema-enabled-roles.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="infoschema-parameters.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="LITERAL" >enabled_roles</TT ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="information-schema.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><TT CLASS="LITERAL" >parameters</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >