<!--
doc/src/sgml/ref/alter_user_mapping.sgml
PostgreSQL documentation
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<refentry id="sql-alterusermapping">
 <indexterm zone="sql-alterusermapping">
  <primary>ALTER USER MAPPING</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>ALTER USER MAPPING</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>ALTER USER MAPPING</refname>
  <refpurpose>change the definition of a user mapping</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
ALTER USER MAPPING FOR { <replaceable class="parameter">user_name</replaceable> | USER | CURRENT_USER | SESSION_USER | PUBLIC }
    SERVER <replaceable class="parameter">server_name</replaceable>
    OPTIONS ( [ ADD | SET | DROP ] <replaceable class="parameter">option</replaceable> ['<replaceable class="parameter">value</replaceable>'] [, ... ] )
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER USER MAPPING</command> changes the definition of a
   user mapping.
  </para>

  <para>
   The owner of a foreign server can alter user mappings for that
   server for any user.  Also, a user can alter a user mapping for
   their own user name if <literal>USAGE</literal> privilege on the server has
   been granted to the user.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">user_name</replaceable></term>
    <listitem>
     <para>
      User name of the mapping. <literal>CURRENT_USER</literal>
      and <literal>USER</literal> match the name of the current
      user. <literal>PUBLIC</literal> is used to match all present and future
      user names in the system.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">server_name</replaceable></term>
    <listitem>
     <para>
      Server name of the user mapping.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>OPTIONS ( [ ADD | SET | DROP ] <replaceable class="parameter">option</replaceable> ['<replaceable class="parameter">value</replaceable>'] [, ... ] )</literal></term>
    <listitem>
     <para>
      Change options for the user mapping. The new options override
      any previously specified
      options.  <literal>ADD</literal>, <literal>SET</literal>, and <literal>DROP</literal>
      specify the action to be performed.  <literal>ADD</literal> is assumed
      if no operation is explicitly specified.  Option names must be
      unique; options are also validated by the server's foreign-data
      wrapper.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Change the password for user mapping <literal>bob</literal>, server <literal>foo</literal>:
<programlisting>
ALTER USER MAPPING FOR bob SERVER foo OPTIONS (SET password 'public');
</programlisting></para>

 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   <command>ALTER USER MAPPING</command> conforms to ISO/IEC 9075-9
   (SQL/MED).  There is a subtle syntax issue: The standard omits
   the <literal>FOR</literal> key word.  Since both <literal>CREATE
   USER MAPPING</literal> and <literal>DROP USER MAPPING</literal> use
   <literal>FOR</literal> in analogous positions, and IBM DB2 (being
   the other major SQL/MED implementation) also requires it
   for <literal>ALTER USER MAPPING</literal>, PostgreSQL diverges from
   the standard here in the interest of consistency and
   interoperability.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-createusermapping"/></member>
   <member><xref linkend="sql-dropusermapping"/></member>
  </simplelist>
 </refsect1>

</refentry>
