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$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_user.sgml,v 1.20 2002/03/01 22:45:07 petere Exp $
PostgreSQL documentation
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<refentry id="SQL-ALTERUSER">
 <refmeta>
  <refentrytitle id="sql-alteruser-title">ALTER USER</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>ALTER USER</refname>
  <refpurpose>change a database user account</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
ALTER USER <replaceable class="PARAMETER">username</replaceable> [ [ WITH ] <replaceable class="PARAMETER">option</replaceable> [ ... ] ]

where <replaceable class="PARAMETER">option</replaceable> can be:

      [ ENCRYPTED | UNENCRYPTED ] PASSWORD '<replaceable class="PARAMETER">password</replaceable>' 
    | CREATEDB | NOCREATEDB
    | CREATEUSER | NOCREATEUSER 
    | VALID UNTIL '<replaceable class="PARAMETER">abstime</replaceable>'

ALTER USER <replaceable class="PARAMETER">username</replaceable> SET <replaceable>variable</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
ALTER USER <replaceable class="PARAMETER">username</replaceable> RESET <replaceable>variable</replaceable>
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER USER</command> is used to change the attributes of a
   <productname>PostgreSQL</productname> user account.  Attributes not
   mentioned in the command retain their previous settings.
  </para>

  <para>
   The first variant of this command in the synopsis changes certain
   global user privileges and authentication settings.  (See below for
   details.)  Only a database superuser can change privileges and
   password expiration with this command.  Ordinary users can only
   change their own password.
  </para>

  <para>
   The second and the third variant change a user's session default of
   a specified configuration variable.  Whenever the user subsequently
   starts a new session, <literal>SET
   <replaceable>variable</replaceable> TO
   <replaceable>value</replaceable></literal> is effectively executed
   before the start of the session.  Ordinary users can change their
   own session defaults.  Superusers can change anyone's session
   defaults.
  </para>

  <refsect2>
   <title>Parameters</title>

   <para>
    <variablelist>
     <varlistentry>
      <term><replaceable class="PARAMETER">username</replaceable></term>
      <listitem>
       <para>
	The name of the user whose attributes are to be altered.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="PARAMETER">password</replaceable></term>
      <listitem>
       <para>
	The new password to be used for this account.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>ENCRYPTED</literal></term>
      <term><literal>UNENCRYPTED</literal></term>
      <listitem>
       <para>
	These key words control whether the password is stored
	encrypted in <literal>pg_shadow</>.  (See
	<xref linkend="SQL-CREATEUSER" endterm="SQL-CREATEUSER-title">
	for more information about this choice.)
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CREATEDB</literal></term>
      <term><literal>NOCREATEDB</literal></term>
      <listitem>
       <para>
	These clauses define a user's ability to create databases.  If
	<literal>CREATEDB</literal> is specified, the user being
	defined will be allowed to create his own databases. Using
	<literal>NOCREATEDB</literal> will deny a user the ability to
	create databases.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CREATEUSER</literal></term>
      <term><literal>NOCREATEUSER</literal></term>
      <listitem>
       <para>
	These clauses determine whether a user will be permitted to
	create new users himself. This option will also make the user
	a superuser who can override all access restrictions.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="PARAMETER">abstime</replaceable></term>
      <listitem>
       <para>
	The date (and, optionally, the time)
	at which this user's password is to expire.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable>variable</replaceable></term>
      <term><replaceable>value</replaceable></term>
      <listitem>
       <para>
        Set this user's session default of the specified configuration
        variable to the given value.  If
        <replaceable>value</replaceable> is <literal>DEFAULT</literal>
        or, equivalently, <literal>RESET</literal> is used, the
        user-specific variable setting is removed and the user will
        inherit the default setting in new sessions.  Use
        <literal>RESET ALL</literal> to clear all settings.
       </para>

       <para>
        See <xref linkend="sql-set" endterm="sql-set-title"> and the
        <citetitle>Administrator's Guide</citetitle> for more
        information about allowed variable names and values.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
   </para>
  </refsect2>
 </refsect1>

 <refsect1>
  <title>Diagnostics</title>

  <para>
   <variablelist>
    <varlistentry>
     <term><computeroutput>ALTER USER</computeroutput></term>
     <listitem>
      <para>
       Message returned if the alteration was successful.
      </para>
     </listitem>
    </varlistentry>
     
    <varlistentry>
     <term><computeroutput>ERROR:  ALTER USER: user "username" does not exist</computeroutput></term>
     <listitem>
      <para>
       Error message returned if the specified user is not known to
       the database.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   Use <xref linkend="SQL-CREATEUSER" endterm="SQL-CREATEUSER-title">
   to add new users, and <xref linkend="SQL-DROPUSER"
   endterm="SQL-DROPUSER-title"> to remoe a user.
  </para>

  <para>
   <command>ALTER USER</command> cannot change a user's group memberships.
   Use <xref linkend="SQL-ALTERGROUP" endterm="SQL-ALTERGROUP-title">
   to do that.
  </para>

  <para>
   Using <xref linkend="sql-alterdatabase"
   endterm="sql-alterdatabase-title">, it is also possible to tie a
   session default to a specific database rather than a user.
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Change a user password:

<programlisting>
ALTER USER davide WITH PASSWORD 'hu8jmn3';
</programlisting>
  </para>

  <para>
   Change a user's valid until date:

<programlisting>
ALTER USER manuel VALID UNTIL 'Jan 31 2030';
</programlisting>
  </para>

  <para>
   Change a user's valid until date, specifying that his
   authorization should expire at midday on 4th May 1998 using
   the time zone which is one hour ahead of UTC:
<programlisting>
ALTER USER chris VALID UNTIL 'May 4 12:00:00 1998 +1';
</programlisting>
  </para>

  <para>
   Give a user the ability to create other users and new databases:

<programlisting>
ALTER USER miriam CREATEUSER CREATEDB;
</programlisting>
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>
    
  <para>
   The <command>ALTER USER</command> statement is a
   <productname>PostgreSQL</productname> extension.  The SQL standard
   leaves the definition of users to the implementation.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-createuser" endterm="sql-createuser-title"></member>
   <member><xref linkend="sql-dropuser" endterm="sql-dropuser-title"></member>
   <member><xref linkend="sql-set" endterm="sql-set-title"></member>
  </simplelist>
 </refsect1>
</refentry>

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