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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="MULTIBYTE"
>20.2. Character Set Support</A
></H1
><A
NAME="AEN20500"
></A
><P
> The character set support in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
allows you to store text in a variety of character sets, including
single-byte character sets such as the ISO 8859 series and
multiple-byte character sets such as <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
> (Extended Unix
Code), Unicode, and Mule internal code. All character sets can be
used transparently throughout the server. (If you use extension
functions from other sources, it depends on whether they wrote
their code correctly.) The default character set is selected while
initializing your <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> database
cluster using <TT
CLASS="COMMAND"
>initdb</TT
>. It can be overridden when you
create a database using <TT
CLASS="COMMAND"
>createdb</TT
> or by using the
SQL command <TT
CLASS="COMMAND"
>CREATE DATABASE</TT
>. So you can have multiple
databases each with a different character set.
</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MULTIBYTE-CHARSET-SUPPORTED"
>20.2.1. Supported Character Sets</A
></H2
><P
> <A
HREF="multibyte.html#CHARSET-TABLE"
>Table 20-1</A
> shows the character sets available
for use in the server.
</P
><DIV
CLASS="TABLE"
><A
NAME="CHARSET-TABLE"
></A
><P
><B
>Table 20-1. Server Character Sets</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
>SQL_ASCII</TT
></TD
><TD
><ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_JP</TT
></TD
><TD
>Japanese <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_CN</TT
></TD
><TD
>Chinese <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_KR</TT
></TD
><TD
>Korean <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>JOHAB</TT
></TD
><TD
>Korean <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
> (Hangle base)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_TW</TT
></TD
><TD
>Taiwan <ACRONYM
CLASS="ACRONYM"
>EUC</ACRONYM
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>UNICODE</TT
></TD
><TD
>Unicode (<ACRONYM
CLASS="ACRONYM"
>UTF</ACRONYM
>-8)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
></TD
><TD
>Mule internal code</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN1</TT
></TD
><TD
>ISO 8859-1/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 94 (Latin alphabet no.1)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN2</TT
></TD
><TD
>ISO 8859-2/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 94 (Latin alphabet no.2)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN3</TT
></TD
><TD
>ISO 8859-3/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 94 (Latin alphabet no.3)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN4</TT
></TD
><TD
>ISO 8859-4/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 94 (Latin alphabet no.4)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN5</TT
></TD
><TD
>ISO 8859-9/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 128 (Latin alphabet no.5)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN6</TT
></TD
><TD
>ISO 8859-10/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 144 (Latin alphabet no.6)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN7</TT
></TD
><TD
>ISO 8859-13 (Latin alphabet no.7)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN8</TT
></TD
><TD
>ISO 8859-14 (Latin alphabet no.8)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN9</TT
></TD
><TD
>ISO 8859-15 (Latin alphabet no.9)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN10</TT
></TD
><TD
>ISO 8859-16/<ACRONYM
CLASS="ACRONYM"
>ASRO</ACRONYM
> SR 14111 (Latin alphabet no.10)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
></TD
><TD
>ISO 8859-5/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 113 (Latin/Cyrillic)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_6</TT
></TD
><TD
>ISO 8859-6/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 114 (Latin/Arabic)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_7</TT
></TD
><TD
>ISO 8859-7/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 118 (Latin/Greek)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_8</TT
></TD
><TD
>ISO 8859-8/<ACRONYM
CLASS="ACRONYM"
>ECMA</ACRONYM
> 121 (Latin/Hebrew)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>KOI8</TT
></TD
><TD
><ACRONYM
CLASS="ACRONYM"
>KOI</ACRONYM
>8-R(U)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ALT</TT
></TD
><TD
>Windows CP866</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN874</TT
></TD
><TD
>Windows CP874 (Thai)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN1250</TT
></TD
><TD
>Windows CP1250</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN</TT
></TD
><TD
>Windows CP1251</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN1256</TT
></TD
><TD
>Windows CP1256 (Arabic)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>TCVN</TT
></TD
><TD
><ACRONYM
CLASS="ACRONYM"
>TCVN</ACRONYM
>-5712/Windows CP1258 (Vietnamese)</TD
></TR
></TBODY
></TABLE
></DIV
><DIV
CLASS="IMPORTANT"
><BLOCKQUOTE
CLASS="IMPORTANT"
><P
><B
>Important: </B
> Before <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 7.2, <TT
CLASS="LITERAL"
>LATIN5</TT
>
mistakenly meant ISO 8859-5. From 7.2 on, <TT
CLASS="LITERAL"
>LATIN5</TT
>
means ISO 8859-9. If you have a <TT
CLASS="LITERAL"
>LATIN5</TT
> database
created on 7.1 or earlier and want to migrate to 7.2 or later,
you should be careful about this change.
</P
></BLOCKQUOTE
></DIV
><P
> Not all <ACRONYM
CLASS="ACRONYM"
>API</ACRONYM
>s support all the listed character sets. For example, the
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
JDBC driver does not support <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>, <TT
CLASS="LITERAL"
>LATIN6</TT
>,
<TT
CLASS="LITERAL"
>LATIN8</TT
>, and <TT
CLASS="LITERAL"
>LATIN10</TT
>.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN20670"
>20.2.2. Setting the Character Set</A
></H2
><P
> <TT
CLASS="COMMAND"
>initdb</TT
> defines the default character set
for a <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> cluster. For example,
</P><PRE
CLASS="SCREEN"
>initdb -E EUC_JP</PRE
><P>
sets the default character set (encoding) to
<TT
CLASS="LITERAL"
>EUC_JP</TT
> (Extended Unix Code for Japanese). You
can use <TT
CLASS="OPTION"
>--encoding</TT
> instead of
<TT
CLASS="OPTION"
>-E</TT
> if you prefer to type longer option strings.
If no <TT
CLASS="OPTION"
>-E</TT
> or <TT
CLASS="OPTION"
>--encoding</TT
> option is
given, <TT
CLASS="LITERAL"
>SQL_ASCII</TT
> is used.
</P
><P
> You can create a database with a different character set:
</P><PRE
CLASS="SCREEN"
>createdb -E EUC_KR korean</PRE
><P>
This will create a database named <TT
CLASS="LITERAL"
>korean</TT
> that
uses the character set <TT
CLASS="LITERAL"
>EUC_KR</TT
>. Another way to
accomplish this is to use this SQL command:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE DATABASE korean WITH ENCODING 'EUC_KR';</PRE
><P>
The encoding for a database is stored in the system catalog
<TT
CLASS="LITERAL"
>pg_database</TT
>. You can see that by using the
<TT
CLASS="OPTION"
>-l</TT
> option or the <TT
CLASS="COMMAND"
>\l</TT
> command
of <TT
CLASS="COMMAND"
>psql</TT
>.
</P><PRE
CLASS="SCREEN"
>$ <KBD
CLASS="USERINPUT"
>psql -l</KBD
>
List of databases
Database | Owner | Encoding
---------------+---------+---------------
euc_cn | t-ishii | EUC_CN
euc_jp | t-ishii | EUC_JP
euc_kr | t-ishii | EUC_KR
euc_tw | t-ishii | EUC_TW
mule_internal | t-ishii | MULE_INTERNAL
regression | t-ishii | SQL_ASCII
template1 | t-ishii | EUC_JP
test | t-ishii | EUC_JP
unicode | t-ishii | UNICODE
(9 rows)</PRE
><P>
</P
><DIV
CLASS="IMPORTANT"
><BLOCKQUOTE
CLASS="IMPORTANT"
><P
><B
>Important: </B
> Although you can specify any encoding you want for a database, it is
unwise to choose an encoding that is not what is expected by the locale
you have selected. The <TT
CLASS="LITERAL"
>LC_COLLATE</TT
> and
<TT
CLASS="LITERAL"
>LC_CTYPE</TT
> settings imply a particular encoding,
and locale-dependent operations (such as sorting) are likely to
misinterpret data that is in an incompatible encoding.
</P
><P
> Since these locale settings are frozen by <TT
CLASS="COMMAND"
>initdb</TT
>, the
apparent flexibility to use different encodings in different databases
of a cluster is more theoretical than real. It is likely that these
mechanisms will be revisited in future versions of
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>.
</P
><P
> One way to use multiple encodings safely is to set the locale to
<TT
CLASS="LITERAL"
>C</TT
> or <TT
CLASS="LITERAL"
>POSIX</TT
> during <TT
CLASS="COMMAND"
>initdb</TT
>, thus
disabling any real locale awareness.
</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN20704"
>20.2.3. Automatic Character Set Conversion Between Server and Client</A
></H2
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> supports automatic
character set conversion between server and client for certain
character sets. The conversion information is stored in the
<TT
CLASS="LITERAL"
>pg_conversion</TT
> system catalog. You can create a new
conversion by using the SQL command <TT
CLASS="COMMAND"
>CREATE
CONVERSION</TT
>. <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> comes with some
predefined conversions. They are listed in <A
HREF="multibyte.html#MULTIBYTE-TRANSLATION-TABLE"
>Table 20-2</A
>.
</P
><DIV
CLASS="TABLE"
><A
NAME="MULTIBYTE-TRANSLATION-TABLE"
></A
><P
><B
>Table 20-2. Client/Server Character Set Conversions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Server Character Set</TH
><TH
>Available Client Character Sets</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
>SQL_ASCII</TT
></TD
><TD
><TT
CLASS="LITERAL"
>SQL_ASCII</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_JP</TT
></TD
><TD
><TT
CLASS="LITERAL"
>EUC_JP</TT
>, <TT
CLASS="LITERAL"
>SJIS</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_CN</TT
></TD
><TD
><TT
CLASS="LITERAL"
>EUC_CN</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_KR</TT
></TD
><TD
><TT
CLASS="LITERAL"
>EUC_KR</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>JOHAB</TT
></TD
><TD
><TT
CLASS="LITERAL"
>JOHAB</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>EUC_TW</TT
></TD
><TD
><TT
CLASS="LITERAL"
>EUC_TW</TT
>, <TT
CLASS="LITERAL"
>BIG5</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN1</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN1</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN2</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN2</TT
>, <TT
CLASS="LITERAL"
>WIN1250</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN3</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN3</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN4</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN4</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN5</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN5</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN6</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN6</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN7</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN7</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN8</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN8</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN9</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN9</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>LATIN10</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN10</TT
>, <TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>,
<TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>,
<TT
CLASS="LITERAL"
>WIN</TT
>,
<TT
CLASS="LITERAL"
>ALT</TT
>,
<TT
CLASS="LITERAL"
>KOI8</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_6</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_6</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_7</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_7</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ISO_8859_8</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_8</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>UNICODE</TT
></TD
><TD
> <TT
CLASS="LITERAL"
>EUC_JP</TT
>, <TT
CLASS="LITERAL"
>SJIS</TT
>,
<TT
CLASS="LITERAL"
>EUC_KR</TT
>, <TT
CLASS="LITERAL"
>UHC</TT
>, <TT
CLASS="LITERAL"
>JOHAB</TT
>,
<TT
CLASS="LITERAL"
>EUC_CN</TT
>, <TT
CLASS="LITERAL"
>GBK</TT
>,
<TT
CLASS="LITERAL"
>EUC_TW</TT
>, <TT
CLASS="LITERAL"
>BIG5</TT
>,
<TT
CLASS="LITERAL"
>LATIN1</TT
> to <TT
CLASS="LITERAL"
>LATIN10</TT
>,
<TT
CLASS="LITERAL"
>ISO_8859_5</TT
>,
<TT
CLASS="LITERAL"
>ISO_8859_6</TT
>,
<TT
CLASS="LITERAL"
>ISO_8859_7</TT
>,
<TT
CLASS="LITERAL"
>ISO_8859_8</TT
>,
<TT
CLASS="LITERAL"
>WIN</TT
>, <TT
CLASS="LITERAL"
>ALT</TT
>,
<TT
CLASS="LITERAL"
>KOI8</TT
>,
<TT
CLASS="LITERAL"
>WIN1256</TT
>,
<TT
CLASS="LITERAL"
>TCVN</TT
>,
<TT
CLASS="LITERAL"
>WIN874</TT
>,
<TT
CLASS="LITERAL"
>GB18030</TT
>,
<TT
CLASS="LITERAL"
>WIN1250</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
></TD
><TD
><TT
CLASS="LITERAL"
>EUC_JP</TT
>, <TT
CLASS="LITERAL"
>SJIS</TT
>, <TT
CLASS="LITERAL"
>EUC_KR</TT
>, <TT
CLASS="LITERAL"
>EUC_CN</TT
>,
<TT
CLASS="LITERAL"
>EUC_TW</TT
>, <TT
CLASS="LITERAL"
>BIG5</TT
>, <TT
CLASS="LITERAL"
>LATIN1</TT
> to <TT
CLASS="LITERAL"
>LATIN5</TT
>,
<TT
CLASS="LITERAL"
>WIN</TT
>, <TT
CLASS="LITERAL"
>ALT</TT
>,
<TT
CLASS="LITERAL"
>WIN1250</TT
>,
<TT
CLASS="LITERAL"
>BIG5</TT
>, <TT
CLASS="LITERAL"
>ISO_8859_5</TT
>, <TT
CLASS="LITERAL"
>KOI8</TT
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>KOI8</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
>, <TT
CLASS="LITERAL"
>WIN</TT
>,
<TT
CLASS="LITERAL"
>ALT</TT
>, <TT
CLASS="LITERAL"
>KOI8</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>ALT</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
>, <TT
CLASS="LITERAL"
>WIN</TT
>,
<TT
CLASS="LITERAL"
>ALT</TT
>, <TT
CLASS="LITERAL"
>KOI8</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN874</TT
></TD
><TD
><TT
CLASS="LITERAL"
>WIN874</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN1250</TT
></TD
><TD
><TT
CLASS="LITERAL"
>LATIN2</TT
>, <TT
CLASS="LITERAL"
>WIN1250</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN</TT
></TD
><TD
><TT
CLASS="LITERAL"
>ISO_8859_5</TT
>, <TT
CLASS="LITERAL"
>WIN</TT
>,
<TT
CLASS="LITERAL"
>ALT</TT
>, <TT
CLASS="LITERAL"
>KOI8</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>, <TT
CLASS="LITERAL"
>MULE_INTERNAL</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>WIN1256</TT
></TD
><TD
><TT
CLASS="LITERAL"
>WIN1256</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>TCVN</TT
></TD
><TD
><TT
CLASS="LITERAL"
>TCVN</TT
>,
<TT
CLASS="LITERAL"
>UNICODE</TT
>
</TD
></TR
></TBODY
></TABLE
></DIV
><P
> To enable the automatic character set conversion, you have to
tell <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> the character set
(encoding) you would like to use in the client. There are several
ways to accomplish this:
<P
></P
></P><UL
><LI
><P
> Using the <TT
CLASS="COMMAND"
>\encoding</TT
> command in
<SPAN
CLASS="APPLICATION"
>psql</SPAN
>.
<TT
CLASS="COMMAND"
>\encoding</TT
> allows you to change client
encoding on the fly. For
example, to change the encoding to <TT
CLASS="LITERAL"
>SJIS</TT
>, type:
</P><PRE
CLASS="PROGRAMLISTING"
>\encoding SJIS</PRE
><P>
</P
></LI
><LI
><P
> Using <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> functions.
<TT
CLASS="COMMAND"
>\encoding</TT
> actually calls
<CODE
CLASS="FUNCTION"
>PQsetClientEncoding()</CODE
> for its purpose.
</P><PRE
CLASS="SYNOPSIS"
>int PQsetClientEncoding(PGconn *<TT
CLASS="REPLACEABLE"
><I
>conn</I
></TT
>, const char *<TT
CLASS="REPLACEABLE"
><I
>encoding</I
></TT
>);</PRE
><P>
where <TT
CLASS="REPLACEABLE"
><I
>conn</I
></TT
> is a connection to the server,
and <TT
CLASS="REPLACEABLE"
><I
>encoding</I
></TT
> is the encoding you
want to use. If the function successfully sets the encoding, it returns 0,
otherwise -1. The current encoding for this connection can be determined by
using:
</P><PRE
CLASS="SYNOPSIS"
>int PQclientEncoding(const PGconn *<TT
CLASS="REPLACEABLE"
><I
>conn</I
></TT
>);</PRE
><P>
Note that it returns the encoding ID, not a symbolic string
such as <TT
CLASS="LITERAL"
>EUC_JP</TT
>. To convert an encoding ID to an encoding name, you
can use:
</P><PRE
CLASS="SYNOPSIS"
>char *pg_encoding_to_char(int <TT
CLASS="REPLACEABLE"
><I
>encoding_id</I
></TT
>);</PRE
><P>
</P
></LI
><LI
><P
> Using <TT
CLASS="COMMAND"
>SET client_encoding TO</TT
>.
Setting the client encoding can be done with this SQL command:
</P><PRE
CLASS="PROGRAMLISTING"
>SET CLIENT_ENCODING TO '<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>';</PRE
><P>
Also you can use the more standard SQL syntax <TT
CLASS="LITERAL"
>SET NAMES</TT
> for this purpose:
</P><PRE
CLASS="PROGRAMLISTING"
>SET NAMES '<TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
>';</PRE
><P>
To query the current client encoding:
</P><PRE
CLASS="PROGRAMLISTING"
>SHOW client_encoding;</PRE
><P>
To return to the default encoding:
</P><PRE
CLASS="PROGRAMLISTING"
>RESET client_encoding;</PRE
><P>
</P
></LI
><LI
><P
> Using <TT
CLASS="ENVAR"
>PGCLIENTENCODING</TT
>. If the environment variable
<TT
CLASS="ENVAR"
>PGCLIENTENCODING</TT
> is defined in the client's
environment, that client encoding is automatically selected
when a connection to the server is made. (This can
subsequently be overridden using any of the other methods
mentioned above.)
</P
></LI
><LI
><P
> Using the configuration variable <A
HREF="runtime-config.html#GUC-CLIENT-ENCODING"
>client_encoding</A
>. If the
<TT
CLASS="VARNAME"
>client_encoding</TT
> variable is set, that client
encoding is automatically selected when a connection to the
server is made. (This can subsequently be overridden using any
of the other methods mentioned above.)
</P
></LI
></UL
><P>
</P
><P
> If the conversion of a particular character is not possible
— suppose you chose <TT
CLASS="LITERAL"
>EUC_JP</TT
> for the
server and <TT
CLASS="LITERAL"
>LATIN1</TT
> for the client, then some
Japanese characters cannot be converted to
<TT
CLASS="LITERAL"
>LATIN1</TT
> — it is transformed to its
hexadecimal byte values in parentheses, e.g.,
<TT
CLASS="LITERAL"
>(826C)</TT
>.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN21010"
>20.2.4. Further Reading</A
></H2
><P
> These are good sources to start learning about various kinds of encoding
systems.
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
HREF="ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf"
TARGET="_top"
>ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf</A
></DT
><DD
><P
> Detailed explanations of <TT
CLASS="LITERAL"
>EUC_JP</TT
>,
<TT
CLASS="LITERAL"
>EUC_CN</TT
>, <TT
CLASS="LITERAL"
>EUC_KR</TT
>,
<TT
CLASS="LITERAL"
>EUC_TW</TT
> appear in section 3.2.
</P
></DD
><DT
><A
HREF="http://www.unicode.org/"
TARGET="_top"
>http://www.unicode.org/</A
></DT
><DD
><P
> The web site of the Unicode Consortium
</P
></DD
><DT
>RFC 2044</DT
><DD
><P
> <ACRONYM
CLASS="ACRONYM"
>UTF</ACRONYM
>-8 is defined here.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
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