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<!-- $PostgreSQL: pgsql/doc/src/sgml/ref/drop_cast.sgml,v 1.7 2006/06/16 22:27:55 adunstan Exp $ -->
<refentry id="SQL-DROPCAST">
<refmeta>
<refentrytitle id="SQL-DROPCAST-TITLE">DROP CAST</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>DROP CAST</refname>
<refpurpose>remove a cast</refpurpose>
</refnamediv>
<indexterm zone="sql-dropcast">
<primary>DROP CAST</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
DROP CAST [ IF EXISTS ] (<replaceable>sourcetype</replaceable> AS <replaceable>targettype</replaceable>) [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
<refsect1 id="sql-dropcast-description">
<title>Description</title>
<para>
<command>DROP CAST</command> removes a previously defined cast.
</para>
<para>
To be able to drop a cast, you must own the source or the target
data type. These are the same privileges that are required to
create a cast.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF EXISTS</literal></term>
<listitem>
<para>
Do not throw an error if the cast does not exist. A notice is issued
in this case.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>sourcetype</replaceable></term>
<listitem>
<para>
The name of the source data type of the cast.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>targettype</replaceable></term>
<listitem>
<para>
The name of the target data type of the cast.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
These key words do not have any effect, since there are no
dependencies on casts.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="sql-dropcast-examples">
<title>Examples</title>
<para>
To drop the cast from type <type>text</type> to type <type>int</type>:
<programlisting>
DROP CAST (text AS int);
</programlisting>
</para>
</refsect1>
<refsect1 id="sql-dropcast-compat">
<title>Compatibility</title>
<para>
The <command>DROP CAST</command> command conforms to the SQL standard.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-createcast" endterm="sql-createcast-title"></member>
</simplelist>
</refsect1>
</refentry>
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