<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Data Types</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="The Information Schema" HREF="information-schema.html"><LINK REL="NEXT" TITLE="information_schema_catalog_name" HREF="infoschema-information-schema-catalog-name.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="information-schema.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-information-schema-catalog-name.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="INFOSCHEMA-DATATYPES" >30.2. Data Types</A ></H1 ><P > The columns of the information schema views use special data types that are defined in the information schema. These are defined as simple domains over ordinary built-in types. You should not use these types for work outside the information schema, but your applications must be prepared for them if they select from the information schema. </P ><P > These types are: <P ></P ></P><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="TYPE" >cardinal_number</TT ></DT ><DD ><P > A nonnegative integer. </P ></DD ><DT ><TT CLASS="TYPE" >character_data</TT ></DT ><DD ><P > A character string (without specific maximum length). </P ></DD ><DT ><TT CLASS="TYPE" >sql_identifier</TT ></DT ><DD ><P > A character string. This type is used for SQL identifiers, the type <TT CLASS="TYPE" >character_data</TT > is used for any other kind of text data. </P ></DD ><DT ><TT CLASS="TYPE" >time_stamp</TT ></DT ><DD ><P > A domain over the type <TT CLASS="TYPE" >timestamp</TT > </P ></DD ></DL ></DIV ><P> Every column in the information schema has one of these four types. </P ><P > Boolean (true/false) data is represented in the information schema by a column of type <TT CLASS="TYPE" >character_data</TT > that contains either <TT CLASS="LITERAL" >YES</TT > or <TT CLASS="LITERAL" >NO</TT >. (The information schema was invented before the type <TT CLASS="TYPE" >boolean</TT > was added to the SQL standard, so this convention is necessary to keep the information schema backward compatible.) </P ></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="information-schema.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-information-schema-catalog-name.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >The Information Schema</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" >information_schema_catalog_name</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >