drop_domain.sgml

postgresql8.3.4源码,开源数据库

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$PostgreSQL: pgsql/doc/src/sgml/ref/drop_domain.sgml,v 1.18 2007/05/15 19:13:55 neilc Exp $
PostgreSQL documentation
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<refentry id="SQL-DROPDOMAIN">
 <refmeta>
  <refentrytitle id="SQL-DROPDOMAIN-TITLE">DROP DOMAIN</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>DROP DOMAIN</refname>
  <refpurpose>remove a domain</refpurpose>
 </refnamediv>

 <indexterm zone="sql-dropdomain">
  <primary>DROP DOMAIN</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
DROP DOMAIN [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>DROP DOMAIN</command> removes a domain.  Only the owner of
   a domain can remove it.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><literal>IF EXISTS</literal></term>
    <listitem>
     <para>
      Do not throw an error if the domain does not exist. A notice is issued 
      in this case.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of an existing domain.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>CASCADE</></term>
    <listitem>
     <para>
      Automatically drop objects that depend on the domain (such as
      table columns).
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>RESTRICT</></term>
    <listitem>
     <para>
      Refuse to drop the domain if any objects depend on it.  This is
      the default.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 id="SQL-DROPDOMAIN-examples">
  <title>Examples</title>

  <para>
   To remove the domain <type>box</type>:

<programlisting>
DROP DOMAIN box;
</programlisting>
  </para>
 </refsect1>

 <refsect1 id="SQL-DROPDOMAIN-compatibility">
  <title>Compatibility</title>
  
  <para>
   This command conforms to the SQL standard, except for the
   <literal>IF EXISTS</> option, which is a <productname>PostgreSQL</> 
   extension.
  </para>
 </refsect1>

 <refsect1 id="SQL-DROPDOMAIN-see-also">
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-createdomain" endterm="sql-createdomain-title"></member>
   <member><xref linkend="sql-alterdomain" endterm="sql-alterdomain-title"></member>
  </simplelist>
 </refsect1>

</refentry>