doc/src/sgml/ref/drop_operator.sgml - master - githubmirror/postgres

doc/src/sgml/ref/drop_operator.sgml
146 строк3 KB
Tom Lane
Remove support for postfix (right-unary) operators.
18 сен 2020, 02:38
18 сен 2020, 02:381ed6b89
<!--
doc/src/sgml/ref/drop_operator.sgml
PostgreSQL documentation
-->

<refentry id="sql-dropoperator">
 <indexterm zone="sql-dropoperator">
  <primary>DROP OPERATOR</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>DROP OPERATOR</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>DROP OPERATOR</refname>
  <refpurpose>remove an operator</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
DROP OPERATOR [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ( { <replaceable class="parameter">left_type</replaceable> | NONE } , <replaceable class="parameter">right_type</replaceable> ) [, ...] [ CASCADE | RESTRICT ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>DROP OPERATOR</command> drops an existing operator from
   the database system.  To execute this command you must be the owner
   of the operator.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>

   <varlistentry>
    <term><literal>IF EXISTS</literal></term>
    <listitem>
     <para>
      Do not throw an error if the operator 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 operator.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">left_type</replaceable></term>
    <listitem>
     <para>
      The data type of the operator's left operand; write
      <literal>NONE</literal> if the operator has no left operand.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">right_type</replaceable></term>
    <listitem>
     <para>
      The data type of the operator's right operand.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>CASCADE</literal></term>
    <listitem>
     <para>
      Automatically drop objects that depend on the operator (such as views
      using it), and in turn all objects that depend on those objects
      (see <xref linkend="ddl-depend"/>).
     </para>
    </listitem>
   </varlistentry>

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

 <refsect1>
  <title>Examples</title>

  <para>
   Remove the power operator <literal>a^b</literal> for type <type>integer</type>:
<programlisting>
DROP OPERATOR ^ (integer, integer);
</programlisting>
  </para>

  <para>
   Remove the bitwise-complement prefix operator
   <literal>~b</literal> for type <type>bit</type>:
<programlisting>
DROP OPERATOR ~ (none, bit);
</programlisting>
  </para>

  <para>
   Remove multiple operators in one command:
<programlisting>
DROP OPERATOR ~ (none, bit), ^ (integer, integer);
</programlisting></para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   There is no <command>DROP OPERATOR</command> statement in the SQL standard.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-createoperator"/></member>
   <member><xref linkend="sql-alteroperator"/></member>
  </simplelist>
 </refsect1>

</refentry>