193 lines
5.4 KiB
Plaintext
193 lines
5.4 KiB
Plaintext
<!--
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doc/src/sgml/ref/drop_function.sgml
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PostgreSQL documentation
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-->
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<refentry id="sql-dropfunction">
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<indexterm zone="sql-dropfunction">
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<primary>DROP FUNCTION</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>DROP FUNCTION</refentrytitle>
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<manvolnum>7</manvolnum>
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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 FUNCTION</refname>
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<refpurpose>remove a function</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) ] [, ...]
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[ CASCADE | RESTRICT ]
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>DROP FUNCTION</command> removes the definition of an existing
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function. To execute this command the user must be the
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owner of the function. The argument types to the
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function must be specified, since several different functions
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can exist with the same name and different argument lists.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><literal>IF EXISTS</literal></term>
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<listitem>
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<para>
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Do not throw an error if the function does not exist. A notice is issued
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in this case.
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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 class="parameter">name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an existing function. If no
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argument list is specified, the name must be unique in its schema.
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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 class="parameter">argmode</replaceable></term>
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<listitem>
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<para>
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The mode of an argument: <literal>IN</literal>, <literal>OUT</literal>,
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<literal>INOUT</literal>, or <literal>VARIADIC</literal>.
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If omitted, the default is <literal>IN</literal>.
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Note that <command>DROP FUNCTION</command> does not actually pay
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any attention to <literal>OUT</literal> arguments, since only the input
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arguments are needed to determine the function's identity.
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So it is sufficient to list the <literal>IN</literal>, <literal>INOUT</literal>,
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and <literal>VARIADIC</literal> arguments.
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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 class="parameter">argname</replaceable></term>
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<listitem>
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<para>
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The name of an argument.
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Note that <command>DROP FUNCTION</command> does not actually pay
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any attention to argument names, since only the argument data
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types are needed to determine the function's identity.
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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 class="parameter">argtype</replaceable></term>
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<listitem>
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<para>
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The data type(s) of the function's arguments (optionally
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schema-qualified), if any.
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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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<listitem>
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<para>
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Automatically drop objects that depend on the function (such as
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operators or triggers),
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and in turn all objects that depend on those objects
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(see <xref linkend="ddl-depend"/>).
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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>RESTRICT</literal></term>
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<listitem>
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<para>
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Refuse to drop the function if any objects depend on it. This
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is the default.
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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-dropfunction-examples">
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<title>Examples</title>
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<para>
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This command removes the square root function:
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<programlisting>
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DROP FUNCTION sqrt(integer);
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</programlisting></para>
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<para>
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Drop multiple functions in one command:
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<programlisting>
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DROP FUNCTION sqrt(integer), sqrt(bigint);
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</programlisting></para>
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<para>
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If the function name is unique in its schema, it can be referred to without
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an argument list:
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<programlisting>
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DROP FUNCTION update_employee_salaries;
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</programlisting>
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Note that this is different from
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<programlisting>
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DROP FUNCTION update_employee_salaries();
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</programlisting>
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which refers to a function with zero arguments, whereas the first variant
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can refer to a function with any number of arguments, including zero, as
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long as the name is unique.
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</para>
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</refsect1>
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<refsect1 id="sql-dropfunction-compatibility">
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<title>Compatibility</title>
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<para>
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This command conforms to the SQL standard, with
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these <productname>PostgreSQL</productname> extensions:
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<itemizedlist>
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<listitem>
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<para>The standard only allows one function to be dropped per command.</para>
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</listitem>
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<listitem>
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<para>The <literal>IF EXISTS</literal> option</para>
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</listitem>
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<listitem>
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<para>The ability to specify argument modes and names</para>
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</listitem>
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</itemizedlist></para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="sql-createfunction"/></member>
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<member><xref linkend="sql-alterfunction"/></member>
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<member><xref linkend="sql-dropprocedure"/></member>
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<member><xref linkend="sql-droproutine"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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