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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >character_sets</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 9.2.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="The Information Schema" HREF="information-schema.html"><LINK REL="PREVIOUS" TITLE="attributes" HREF="infoschema-attributes.html"><LINK REL="NEXT" TITLE="check_constraint_routine_usage" HREF="infoschema-check-constraint-routine-usage.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="2017-11-06T22:43:11"></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" ><A HREF="index.html" >PostgreSQL 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="attributes" HREF="infoschema-attributes.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="information-schema.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 34. The Information Schema</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="check_constraint_routine_usage" HREF="infoschema-check-constraint-routine-usage.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="INFOSCHEMA-CHARACTER-SETS" >34.7. <TT CLASS="LITERAL" >character_sets</TT ></A ></H1 ><P > The view <TT CLASS="LITERAL" >character_sets</TT > identifies the character sets available in the current database. Since PostgreSQL does not support multiple character sets within one database, this view only shows one, which is the database encoding. </P ><P > Take note of how the following terms are used in the SQL standard: <P ></P ></P><DIV CLASS="VARIABLELIST" ><DL ><DT >character repertoire</DT ><DD ><P > An abstract collection of characters, for example <TT CLASS="LITERAL" >UNICODE</TT >, <TT CLASS="LITERAL" >UCS</TT >, or <TT CLASS="LITERAL" >LATIN1</TT >. Not exposed as an SQL object, but visible in this view. </P ></DD ><DT >character encoding form</DT ><DD ><P > An encoding of some character repertoire. Most older character repertoires only use one encoding form, and so there are no separate names for them (e.g., <TT CLASS="LITERAL" >LATIN1</TT > is an encoding form applicable to the <TT CLASS="LITERAL" >LATIN1</TT > repertoire). But for example Unicode has the encoding forms <TT CLASS="LITERAL" >UTF8</TT >, <TT CLASS="LITERAL" >UTF16</TT >, etc. (not all supported by PostgreSQL). Encoding forms are not exposed as an SQL object, but are visible in this view. </P ></DD ><DT >character set</DT ><DD ><P > A named SQL object that identifies a character repertoire, a character encoding, and a default collation. A predefined character set would typically have the same name as an encoding form, but users could define other names. For example, the character set <TT CLASS="LITERAL" >UTF8</TT > would typically identify the character repertoire <TT CLASS="LITERAL" >UCS</TT >, encoding form <TT CLASS="LITERAL" >UTF8</TT >, and some default collation. </P ></DD ></DL ></DIV ><P> You can think of an <SPAN CLASS="QUOTE" >"encoding"</SPAN > in PostgreSQL either as a character set or a character encoding form. They will have the same name, and there can only be one in one database. </P ><DIV CLASS="TABLE" ><A NAME="AEN47186" ></A ><P ><B >Table 34-5. <TT CLASS="LITERAL" >character_sets</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" >character_set_catalog</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Character sets are currently not implemented as schema objects, so this column is null.</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >character_set_schema</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Character sets are currently not implemented as schema objects, so this column is null.</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >character_set_name</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Name of the character set, currently implemented as showing the name of the database encoding</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >character_repertoire</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Character repertoire, showing <TT CLASS="LITERAL" >UCS</TT > if the encoding is <TT CLASS="LITERAL" >UTF8</TT >, else just the encoding name</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >form_of_use</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Character encoding form, same as the database encoding</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >default_collate_catalog</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Name of the database containing the default collation (always the current database, if any collation is identified)</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >default_collate_schema</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD >Name of the schema containing the default collation</TD ></TR ><TR ><TD ><TT CLASS="LITERAL" >default_collate_name</TT ></TD ><TD ><TT CLASS="LITERAL" >sql_identifier</TT ></TD ><TD > Name of the default collation. The default collation is identified as the collation that matches the <TT CLASS="LITERAL" >COLLATE</TT > and <TT CLASS="LITERAL" >CTYPE</TT > settings of the current database. If there is no such collation, then this column and the associated schema and catalog columns are null. </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-attributes.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-check-constraint-routine-usage.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="LITERAL" >attributes</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" >check_constraint_routine_usage</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >