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<title>21.2.Character Set Support</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="multibyte"></a>21.2.Character Set Support</h2></div></div></div>
<a name="id663704"></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), UTF-8, 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 <code class="command">initdb</code>. It can be overridden when you
create a database using <code class="command">createdb</code> or by using the
SQL command <code class="command">CREATE DATABASE</code>. So you can have multiple
databases each with a different character set.
</p>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="multibyte-charset-supported"></a>21.2.1.Supported Character Sets</h3></div></div></div>
<p> <a href="multibyte.html#charset-table" title="Table21.1.Server Character Sets">Table21.1, “Server Character Sets”</a> shows the character sets available
for use in the server.
</p>
<div class="table">
<a name="charset-table"></a><p class="title"><b>Table21.1.Server Character Sets</b></p>
<div class="table-contents"><table summary="Server Character Sets" border="1">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>Name</th>
<th>Description</th>
<th>Language</th>
<th>Bytes/Char</th>
<th>Aliases</th>
</tr></thead>
<tbody>
<tr>
<td><code class="literal">BIG5</code></td>
<td>Big Five</td>
<td>Traditional Chinese</td>
<td>1-2</td>
<td>
<code class="literal">WIN950</code>, <code class="literal">Windows950</code>
</td>
</tr>
<tr>
<td><code class="literal">EUC_CN</code></td>
<td>Extended UNIX Code-CN</td>
<td>Simplified Chinese</td>
<td>1-3</td>
<td></td>
</tr>
<tr>
<td><code class="literal">EUC_JP</code></td>
<td>Extended UNIX Code-JP</td>
<td>Japanese</td>
<td>1-3</td>
<td></td>
</tr>
<tr>
<td><code class="literal">EUC_KR</code></td>
<td>Extended UNIX Code-KR</td>
<td>Korean</td>
<td>1-3</td>
<td></td>
</tr>
<tr>
<td><code class="literal">EUC_TW</code></td>
<td>Extended UNIX Code-TW</td>
<td>Traditional Chinese, Taiwanese</td>
<td>1-3</td>
<td></td>
</tr>
<tr>
<td><code class="literal">GB18030</code></td>
<td>National Standard</td>
<td>Chinese</td>
<td>1-2</td>
<td></td>
</tr>
<tr>
<td><code class="literal">GBK</code></td>
<td>Extended National Standard</td>
<td>Simplified Chinese</td>
<td>1-2</td>
<td>
<code class="literal">WIN936</code>, <code class="literal">Windows936</code>
</td>
</tr>
<tr>
<td><code class="literal">ISO_8859_5</code></td>
<td>ISO 8859-5, <acronym class="acronym">ECMA</acronym> 113</td>
<td>Latin/Cyrillic</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">ISO_8859_6</code></td>
<td>ISO 8859-6, <acronym class="acronym">ECMA</acronym> 114</td>
<td>Latin/Arabic</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">ISO_8859_7</code></td>
<td>ISO 8859-7, <acronym class="acronym">ECMA</acronym> 118</td>
<td>Latin/Greek</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">ISO_8859_8</code></td>
<td>ISO 8859-8, <acronym class="acronym">ECMA</acronym> 121</td>
<td>Latin/Hebrew</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">JOHAB</code></td>
<td><acronym class="acronym">JOHAB</acronym></td>
<td>Korean (Hangul)</td>
<td>1-3</td>
<td></td>
</tr>
<tr>
<td><code class="literal">KOI8</code></td>
<td>
<acronym class="acronym">KOI</acronym>8-R(U)</td>
<td>Cyrillic</td>
<td>1</td>
<td><code class="literal">KOI8R</code></td>
</tr>
<tr>
<td><code class="literal">LATIN1</code></td>
<td>ISO 8859-1, <acronym class="acronym">ECMA</acronym> 94</td>
<td>Western European</td>
<td>1</td>
<td><code class="literal">ISO88591</code></td>
</tr>
<tr>
<td><code class="literal">LATIN2</code></td>
<td>ISO 8859-2, <acronym class="acronym">ECMA</acronym> 94</td>
<td>Central European</td>
<td>1</td>
<td><code class="literal">ISO88592</code></td>
</tr>
<tr>
<td><code class="literal">LATIN3</code></td>
<td>ISO 8859-3, <acronym class="acronym">ECMA</acronym> 94</td>
<td>South European</td>
<td>1</td>
<td><code class="literal">ISO88593</code></td>
</tr>
<tr>
<td><code class="literal">LATIN4</code></td>
<td>ISO 8859-4, <acronym class="acronym">ECMA</acronym> 94</td>
<td>North European</td>
<td>1</td>
<td><code class="literal">ISO88594</code></td>
</tr>
<tr>
<td><code class="literal">LATIN5</code></td>
<td>ISO 8859-9, <acronym class="acronym">ECMA</acronym> 128</td>
<td>Turkish</td>
<td>1</td>
<td><code class="literal">ISO88599</code></td>
</tr>
<tr>
<td><code class="literal">LATIN6</code></td>
<td>ISO 8859-10, <acronym class="acronym">ECMA</acronym> 144</td>
<td>Nordic</td>
<td>1</td>
<td><code class="literal">ISO885910</code></td>
</tr>
<tr>
<td><code class="literal">LATIN7</code></td>
<td>ISO 8859-13</td>
<td>Baltic</td>
<td>1</td>
<td><code class="literal">ISO885913</code></td>
</tr>
<tr>
<td><code class="literal">LATIN8</code></td>
<td>ISO 8859-14</td>
<td>Celtic</td>
<td>1</td>
<td><code class="literal">ISO885914</code></td>
</tr>
<tr>
<td><code class="literal">LATIN9</code></td>
<td>ISO 8859-15</td>
<td>LATIN1 with Euro and accents</td>
<td>1</td>
<td>ISO885915</td>
</tr>
<tr>
<td><code class="literal">LATIN10</code></td>
<td>ISO 8859-16, <acronym class="acronym">ASRO</acronym> SR 14111</td>
<td>Romanian</td>
<td>1</td>
<td><code class="literal">ISO885916</code></td>
</tr>
<tr>
<td><code class="literal">MULE_INTERNAL</code></td>
<td>Mule internal code</td>
<td>Multilingual Emacs</td>
<td>1-4</td>
<td></td>
</tr>
<tr>
<td><code class="literal">SJIS</code></td>
<td>Shift JIS</td>
<td>Japanese</td>
<td>1-2</td>
<td>
<code class="literal">Mskanji</code>, <code class="literal">ShiftJIS</code>, <code class="literal">WIN932</code>, <code class="literal">Windows932</code>
</td>
</tr>
<tr>
<td><code class="literal">SQL_ASCII</code></td>
<td>unspecified (see text)</td>
<td><span class="emphasis"><em>any</em></span></td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">UHC</code></td>
<td>Unified Hangul Code</td>
<td>Korean</td>
<td>1-2</td>
<td>
<code class="literal">WIN949</code>, <code class="literal">Windows949</code>
</td>
</tr>
<tr>
<td><code class="literal">UTF8</code></td>
<td>Unicode, 8-bit</td>
<td><span class="emphasis"><em>all</em></span></td>
<td>1-4</td>
<td><code class="literal">Unicode</code></td>
</tr>
<tr>
<td><code class="literal">WIN866</code></td>
<td>Windows CP866</td>
<td>Cyrillic</td>
<td>1</td>
<td><code class="literal">ALT</code></td>
</tr>
<tr>
<td><code class="literal">WIN874</code></td>
<td>Windows CP874</td>
<td>Thai</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">WIN1250</code></td>
<td>Windows CP1250</td>
<td>Central European</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">WIN1251</code></td>
<td>Windows CP1251</td>
<td>Cyrillic</td>
<td>1</td>
<td><code class="literal">WIN</code></td>
</tr>
<tr>
<td><code class="literal">WIN1252</code></td>
<td>Windows CP1252</td>
<td>Western European</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">WIN1256</code></td>
<td>Windows CP1256</td>
<td>Arabic</td>
<td>1</td>
<td></td>
</tr>
<tr>
<td><code class="literal">WIN1258</code></td>
<td>Windows CP1258</td>
<td>Vietnamese</td>
<td>1</td>
<td>
<code class="literal">ABC</code>, <code class="literal">TCVN</code>, <code class="literal">TCVN5712</code>, <code class="literal">VSCII</code>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><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 <code class="literal">MULE_INTERNAL</code>, <code class="literal">LATIN6</code>,
<code class="literal">LATIN8</code>, and <code class="literal">LATIN10</code>.
</p>
<p> The <code class="literal">SQL_ASCII</code> setting behaves considerably differently
from the other settings. When the server character set is
<code class="literal">SQL_ASCII</code>, the server interprets byte values 0-127
according to the ASCII standard, while byte values 128-255 are taken
as uninterpreted characters. No encoding conversion will be done when
the setting is <code class="literal">SQL_ASCII</code>. Thus, this setting is not so
much a declaration that a specific encoding is in use, as a declaration
of ignorance about the encoding. In most cases, if you are
working with any non-ASCII data, it is unwise to use the
<code class="literal">SQL_ASCII</code> setting, because
<span class="productname">PostgreSQL</span> will be unable to help you by
converting or validating non-ASCII characters.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id664688"></a>21.2.2.Setting the Character Set</h3></div></div></div>
<p> <code class="command">initdb</code> 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
<code class="literal">EUC_JP</code> (Extended Unix Code for Japanese). You
can use <code class="option">--encoding</code> instead of
<code class="option">-E</code> if you prefer to type longer option strings.
If no <code class="option">-E</code> or <code class="option">--encoding</code> option is
given, <code class="command">initdb</code> attempts to determine the appropriate
encoding to use based on the specified or default locale.
</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 <code class="literal">korean</code> that
uses the character set <code class="literal">EUC_KR</code>. 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
<code class="literal">pg_database</code>. You can see that by using the
<code class="option">-l</code> option or the <code class="command">\l</code> command
of <code class="command">psql</code>.
</p>
<pre class="screen">$ <strong class="userinput"><code>psql -l</code></strong>
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
postgres | t-ishii | EUC_JP
regression | t-ishii | SQL_ASCII
template1 | t-ishii | EUC_JP
test | t-ishii | EUC_JP
utf8 | t-ishii | UTF8
(9 rows)</pre>
<p>
</p>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Important</h3>
<p> 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 <code class="literal">LC_COLLATE</code> and
<code class="literal">LC_CTYPE</code> 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 <code class="command">initdb</code>, 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
<code class="literal">C</code> or <code class="literal">POSIX</code> during <code class="command">initdb</code>, thus
disabling any real locale awareness.
</p>
</div>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id664905"></a>21.2.3.Automatic Character Set Conversion Between Server and Client</h3></div></div></div>
<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
<code class="literal">pg_conversion</code> system catalog. You can create a new
conversion by using the SQL command <code class="command">CREATE
CONVERSION</code>. <span class="productname">PostgreSQL</span> comes with some
predefined conversions. They are listed in <a href="multibyte.html#multibyte-translation-table" title="Table21.2.Client/Server Character Set Conversions">Table21.2, “Client/Server Character Set Conversions”</a>.
</p>
<div class="table">
<a name="multibyte-translation-table"></a><p class="title"><b>Table21.2.Client/Server Character Set Conversions</b></p>
<div class="table-contents"><table summary="Client/Server Character Set Conversions" border="1">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>Server Character Set</th>
<th>Available Client Character Sets</th>
</tr></thead>
<tbody>
<tr>
<td><code class="literal">BIG5</code></td>
<td>
<span class="emphasis"><em>not supported as a server encoding</em></span>
</td>
</tr>
<tr>
<td><code class="literal">EUC_CN</code></td>
<td>
<span class="emphasis"><em>EUC_CN</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">EUC_JP</code></td>
<td>
<span class="emphasis"><em>EUC_JP</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">SJIS</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">EUC_KR</code></td>
<td>
<span class="emphasis"><em>EUC_KR</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">EUC_TW</code></td>
<td>
<span class="emphasis"><em>EUC_TW</em></span>,
<code class="literal">BIG5</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">GB18030</code></td>
<td>
<span class="emphasis"><em>not supported as a server encoding</em></span>
</td>
</tr>
<tr>
<td><code class="literal">GBK</code></td>
<td>
<span class="emphasis"><em>not supported as a server encoding</em></span>
</td>
</tr>
<tr>
<td><code class="literal">ISO_8859_5</code></td>
<td>
<span class="emphasis"><em>ISO_8859_5</em></span>,
<code class="literal">KOI8</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>,
<code class="literal">WIN866</code>,
<code class="literal">WIN1251</code>
</td>
</tr>
<tr>
<td><code class="literal">ISO_8859_6</code></td>
<td>
<span class="emphasis"><em>ISO_8859_6</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">ISO_8859_7</code></td>
<td>
<span class="emphasis"><em>ISO_8859_7</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">ISO_8859_8</code></td>
<td>
<span class="emphasis"><em>ISO_8859_8</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">JOHAB</code></td>
<td>
<span class="emphasis"><em>JOHAB</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">KOI8</code></td>
<td>
<span class="emphasis"><em>KOI8</em></span>,
<code class="literal">ISO_8859_5</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>,
<code class="literal">WIN866</code>,
<code class="literal">WIN1251</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN1</code></td>
<td>
<span class="emphasis"><em>LATIN1</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN2</code></td>
<td>
<span class="emphasis"><em>LATIN2</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>,
<code class="literal">WIN1250</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN3</code></td>
<td>
<span class="emphasis"><em>LATIN3</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN4</code></td>
<td>
<span class="emphasis"><em>LATIN4</em></span>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN5</code></td>
<td>
<span class="emphasis"><em>LATIN5</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN6</code></td>
<td>
<span class="emphasis"><em>LATIN6</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN7</code></td>
<td>
<span class="emphasis"><em>LATIN7</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN8</code></td>
<td>
<span class="emphasis"><em>LATIN8</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN9</code></td>
<td>
<span class="emphasis"><em>LATIN9</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">LATIN10</code></td>
<td>
<span class="emphasis"><em>LATIN10</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">MULE_INTERNAL</code></td>
<td>
<span class="emphasis"><em>MULE_INTERNAL</em></span>,
<code class="literal">BIG5</code>,
<code class="literal">EUC_CN</code>,
<code class="literal">EUC_JP</code>,
<code class="literal">EUC_KR</code>,
<code class="literal">EUC_TW</code>,
<code class="literal">ISO_8859_5</code>,
<code class="literal">KOI8</code>,
<code class="literal">LATIN1</code> to <code class="literal">LATIN4</code>,
<code class="literal">SJIS</code>,
<code class="literal">WIN866</code>,
<code class="literal">WIN1250</code>,
<code class="literal">WIN1251</code>
</td>
</tr>
<tr>
<td><code class="literal">SJIS</code></td>
<td>
<span class="emphasis"><em>not supported as a server encoding</em></span>
</td>
</tr>
<tr>
<td><code class="literal">SQL_ASCII</code></td>
<td>
<span class="emphasis"><em>any (no conversion will be performed)</em></span>
</td>
</tr>
<tr>
<td><code class="literal">UHC</code></td>
<td>
<span class="emphasis"><em>not supported as a server encoding</em></span>
</td>
</tr>
<tr>
<td><code class="literal">UTF8</code></td>
<td>
<span class="emphasis"><em>all supported encodings</em></span>
</td>
</tr>
<tr>
<td><code class="literal">WIN866</code></td>
<td>
<span class="emphasis"><em>WIN866</em></span>,
<code class="literal">ISO_8859_5</code>,
<code class="literal">KOI8</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>,
<code class="literal">WIN1251</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN874</code></td>
<td>
<span class="emphasis"><em>WIN874</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN1250</code></td>
<td>
<span class="emphasis"><em>WIN1250</em></span>,
<code class="literal">LATIN2</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN1251</code></td>
<td>
<span class="emphasis"><em>WIN1251</em></span>,
<code class="literal">ISO_8859_5</code>,
<code class="literal">KOI8</code>,
<code class="literal">MULE_INTERNAL</code>,
<code class="literal">UTF8</code>,
<code class="literal">WIN866</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN1252</code></td>
<td>
<span class="emphasis"><em>WIN1252</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN1256</code></td>
<td>
<span class="emphasis"><em>WIN1256</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
<tr>
<td><code class="literal">WIN1258</code></td>
<td>
<span class="emphasis"><em>WIN1258</em></span>,
<code class="literal">UTF8</code>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><p> To enable 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>
<div class="itemizedlist"><ul type="disc">
<li>
<p> Using the <code class="command">\encoding</code> command in
<span class="application">psql</span>.
<code class="command">\encoding</code> allows you to change client
encoding on the fly. For
example, to change the encoding to <code class="literal">SJIS</code>, type:
</p>
<pre class="programlisting">\encoding SJIS</pre>
<p>
</p>
</li>
<li>
<p> Using <span class="application">libpq</span> functions.
<code class="command">\encoding</code> actually calls
<code class="function">PQsetClientEncoding()</code> for its purpose.
</p>
<pre class="synopsis">int PQsetClientEncoding(PGconn *<em class="replaceable"><code>conn</code></em>, const char *<em class="replaceable"><code>encoding</code></em>);</pre>
<p>
where <em class="replaceable"><code>conn</code></em> is a connection to the server,
and <em class="replaceable"><code>encoding</code></em> 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 *<em class="replaceable"><code>conn</code></em>);</pre>
<p>
Note that it returns the encoding ID, not a symbolic string
such as <code class="literal">EUC_JP</code>. To convert an encoding ID to an encoding name, you
can use:
</p>
<pre class="synopsis">char *pg_encoding_to_char(int <em class="replaceable"><code>encoding_id</code></em>);</pre>
<p>
</p>
</li>
<li>
<p> Using <code class="command">SET client_encoding TO</code>.
Setting the client encoding can be done with this SQL command:
</p>
<pre class="programlisting">SET CLIENT_ENCODING TO '<em class="replaceable"><code>value</code></em>';</pre>
<p>
Also you can use the more standard SQL syntax <code class="literal">SET NAMES</code> for this purpose:
</p>
<pre class="programlisting">SET NAMES '<em class="replaceable"><code>value</code></em>';</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 <code class="envar">PGCLIENTENCODING</code>. If the environment variable
<code class="envar">PGCLIENTENCODING</code> 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-client.html#guc-client-encoding">client_encoding</a>. If the
<code class="varname">client_encoding</code> 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></div>
<p>
</p>
<p> If the conversion of a particular character is not possible
[mdash ] suppose you chose <code class="literal">EUC_JP</code> for the
server and <code class="literal">LATIN1</code> for the client, then some
Japanese characters cannot be converted to
<code class="literal">LATIN1</code> [mdash ] it is transformed to its
hexadecimal byte values in parentheses, e.g.,
<code class="literal">(826C)</code>.
</p>
<p> If the client character set is defined as <code class="literal">SQL_ASCII</code>,
encoding conversion is disabled, regardless of the server's character
set. Just as for the server, use of <code class="literal">SQL_ASCII</code> is unwise
unless you are working with all-ASCII data.
</p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id666163"></a>21.2.4.Further Reading</h3></div></div></div>
<p> These are good sources to start learning about various kinds of encoding
systems.
</p>
<div class="variablelist"><dl>
<dt><span class="term"><a href="http://www.i18ngurus.com/docs/984813247.html" target="_top">http://www.i18ngurus.com/docs/984813247.html</a></span></dt>
<dd><p> An extensive collection of documents about character sets, encodings,
and code pages.
</p></dd>
<dt><span class="term"><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></span></dt>
<dd><p> Detailed explanations of <code class="literal">EUC_JP</code>,
<code class="literal">EUC_CN</code>, <code class="literal">EUC_KR</code>,
<code class="literal">EUC_TW</code> appear in section 3.2.
</p></dd>
<dt><span class="term"><a href="http://www.unicode.org/" target="_top">http://www.unicode.org/</a></span></dt>
<dd><p> The web site of the Unicode Consortium
</p></dd>
<dt><span class="term">RFC 2044</span></dt>
<dd><p> <acronym class="acronym">UTF</acronym>-8 is defined here.
</p></dd>
</dl></div>
<p>
</p>
</div>
</div></body>
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