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97377048b4
extension to create binary compatible casts. Includes dependency tracking as well. pg_proc.proimplicit is now defunct, but will be removed in a separate commit. pg_dump provides a migration path from the previous scheme to declare casts. Dumping binary compatible casts is currently impossible, though.
134 lines
2.9 KiB
Plaintext
134 lines
2.9 KiB
Plaintext
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/drop_cast.sgml,v 1.1 2002/07/18 23:11:27 petere Exp $ -->
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<refentry id="SQL-DROPCAST">
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<refmeta>
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<refentrytitle id="SQL-DROPCAST-TITLE">DROP CAST</refentrytitle>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>DROP CAST</refname>
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<refpurpose>remove a user-defined cast</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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DROP CAST (<replaceable>sourcetype</replaceable> AS <replaceable>targettype</replaceable>)
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[ CASCADE | RESTRICT ]
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</synopsis>
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</refsynopsisdiv>
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<refsect1 id="sql-dropcast-description">
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<title>Description</title>
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<para>
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<command>DROP CAST</command> removes a previously defined cast.
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</para>
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<para>
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To be able to drop a cast, you must own the underlying function.
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To be able to drop a binary compatible cast, you must own both the
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source and the target data type. These are the same privileges
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that are required to create a cast.
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</para>
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<variablelist>
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<title>Parameters</title>
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<varlistentry>
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<term><replaceable>sourcetype</replaceable></term>
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<listitem>
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<para>
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The name of the source data type of the cast.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>targettype</replaceable></term>
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<listitem>
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<para>
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The name of the target data type of the cast.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>CASCADE</literal></term>
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<term><literal>RESTRICT</literal></term>
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<listitem>
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<para>
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These key words do not have any effect, since there are no
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dependencies on casts.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="sql-dropcast-notes">
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<title>Notes</title>
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<para>
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Use <command>CREATE CAST</command> to create user-defined casts.
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</para>
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<para>
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The privileges required to drop a cast may be changed in a future
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release.
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</para>
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</refsect1>
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<refsect1 id="sql-dropcast-examples">
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<title>Examples</title>
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<para>
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To drop the cast from type <type>text</type> to type <type>int</type>:
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<programlisting>
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DROP CAST (text AS int4);
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</programlisting>
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</para>
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</refsect1>
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<refsect1 id="sql-dropcast-compat">
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<title>Compatibility</title>
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<para>
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The <command>DROP CAST</command> command conforms to SQL99.
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</para>
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</refsect1>
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<refsect1 id="sql-dropcast-seealso">
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<title>See Also</title>
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<para>
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<xref linkend="sql-createcast" endterm="sql-createcast-title">
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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sgml-default-dtd-file:"../reference.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:("/usr/lib/sgml/catalog")
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End:
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