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<refentry id="SQL-GRANT">
 <refmeta>
  <refentrytitle id="sql-grant-title">GRANT</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>GRANT</refname>
  <refpurpose>define access privileges</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
GRANT { { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER } [,...] | ALL [ PRIVILEGES ] }
    ON [ TABLE ] <replaceable class="PARAMETER">objectname</replaceable> [, ...]
    TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
</synopsis>
 </refsynopsisdiv>

 <refsect1 id="sql-grant-description">
  <title>Description</title>

  <para>
   The <command>GRANT</command> command gives specific permissions on
   an object (table, view, sequence) to one or more users or groups of users.
   These permissions are added to those already granted, if any.
  </para>

  <para>
   The key word <literal>PUBLIC</literal> indicates that the
   privileges are to be granted to all users, including those that may
   be created later.  <literal>PUBLIC</literal> may be thought of as an
   implicitly defined group that always includes all users.
   Note that any particular user will have the sum
   of privileges granted directly to him, privileges granted to any group he
   is presently a member of, and privileges granted to
   <literal>PUBLIC</literal>.
  </para>

  <para>
   Users other than the creator of an object do not have any access privileges
   to the object unless the creator grants permissions.
   There is no need to grant privileges to the creator of an object,
   as the creator automatically holds all privileges.
   (The creator could, however, choose to revoke
   some of his own privileges for safety.  Note that the ability to
   grant and revoke privileges is inherent in the creator and cannot
   be lost.  The right to drop the object is likewise inherent in the
   creator, and cannot be granted or revoked.)
  </para>

  <para>
   The possible privileges are:

   <variablelist>
    <varlistentry>
     <term>SELECT</term>
     <listitem>
      <para>
       Allows <xref linkend="sql-select" endterm="sql-select-title"> from any column of the
       specified table, view, or sequence.  Also allows the use of
       <xref linkend="sql-copy" endterm="sql-copy-title"> FROM.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>INSERT</term>
     <listitem>
      <para>
       Allows <xref linkend="sql-insert" endterm="sql-insert-title"> of a new row into the
       specified table.  Also allows <xref linkend="sql-copy" endterm="sql-copy-title"> TO.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>UPDATE</term>
     <listitem>
      <para>
       Allows <xref linkend="sql-update" endterm="sql-update-title"> of any column of the
       specified table.  <literal>SELECT ... FOR UPDATE</literal>
       also requires this privilege (besides the
       <literal>SELECT</literal> privilege).  For sequences, this
       privilege allows the use of <function>nextval</function>,
       <function>currval</function> and <function>setval</function>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>DELETE</term>
     <listitem>
      <para>
       Allows <xref linkend="sql-delete" endterm="sql-delete-title"> of a row from the
       specified table.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>RULE</term>
     <listitem>
      <para>
       Allows the creation of a rule on the table/view.  (See <xref
       linkend="sql-createrule" endterm="sql-createrule-title"> statement.)
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>REFERENCES</term>
     <listitem>
      <para>
       To create a table with a foreign key constraint, it is
       necessary to have this privilege on the table with the referenced
       key.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>TRIGGER</term>
     <listitem>
      <para>
       Allows the creation of a trigger on the specified table.  (See
       <xref linkend="sql-createtrigger" endterm="sql-createtrigger-title"> statement.)
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term>ALL PRIVILEGES</term>
     <listitem>
      <para>
       Grant all of the above privileges at once.  The
       <literal>PRIVILEGES</literal> key word is optional in
       <productname>PostgreSQL</productname>, though it is
       required by strict SQL.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>

   The privileges required by other commands are listed on the
   reference page of the respective command.
  </para>
 </refsect1>


 <refsect1 id="SQL-GRANT-notes">
  <title>Notes</title>

   <para>
    It should be noted that database <firstterm>superusers</> can access
    all objects regardless of object privilege settings.  This
    is comparable to the rights of <literal>root</> in a Unix system.
    As with <literal>root</>, it's unwise to operate as a superuser
    except when absolutely necessary.
   </para>

   <para>
    Currently, to grant privileges in <productname>PostgreSQL</productname>
    to only a few columns, you must
    create a view having the desired columns and then grant privileges
    to that view.
   </para>

   <para>
    Use <xref linkend="app-psql">'s <command>\z</command> command
    to obtain information about privileges
    on existing objects:
<programlisting>
          Database    = lusitania
   +------------------+---------------------------------------------+
   |  Relation        |        Grant/Revoke Permissions             |
   +------------------+---------------------------------------------+
   | mytable          | {"=rw","miriam=arwdRxt","group todos=rw"}   |
   +------------------+---------------------------------------------+
   Legend:
         uname=arwR -- privileges granted to a user
   group gname=arwR -- privileges granted to a group
              =arwR -- privileges granted to PUBLIC

                  r -- SELECT ("read")
                  w -- UPDATE ("write")
                  a -- INSERT ("append")
                  d -- DELETE
                  R -- RULE
                  x -- REFERENCES
                  t -- TRIGGER
            arwdRxt -- ALL PRIVILEGES
</programlisting>
   </para>

   <para>
    The <xref linkend="sql-revoke" endterm="sql-revoke-title"> command is used to revoke access
    privileges.
   </para>
 </refsect1>

 <refsect1 id="sql-grant-examples">
  <title>Examples</title>

  <para>
   Grant insert privilege to all users on table films:

<programlisting>
GRANT INSERT ON films TO PUBLIC;
</programlisting>
  </para>

  <para>
   Grant all privileges to user <literal>manuel</literal> on view <literal>kinds</literal>:

<programlisting>
GRANT ALL PRIVILEGES ON kinds TO manuel;
</programlisting>
  </para>
 </refsect1>

 <refsect1 id="sql-grant-compatibility">
  <title>Compatibility</title>
    
  <refsect2>
   <title>SQL92</title>

   <para>
    The <literal>PRIVILEGES</literal> key word in <literal>ALL
    PRIVILEGES</literal> is required.  <acronym>SQL</acronym> does not
    support setting the privileges on more than one table per command.
   </para>

   <para>
    The <acronym>SQL92</acronym> syntax for GRANT allows setting
    privileges for individual columns within a table, and allows
    setting a privilege to grant the same privileges to others:

<synopsis>
GRANT <replaceable class="PARAMETER">privilege</replaceable> [, ...]
    ON <replaceable class="PARAMETER">object</replaceable> [ ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) ] [, ...]
    TO { PUBLIC | <replaceable class="PARAMETER">username</replaceable> [, ...] } [ WITH GRANT OPTION ]
</synopsis>
   </para>

   <para>
    <acronym>SQL</acronym> allows to grant the USAGE privilege on
    other kinds of objects:  CHARACTER SET, COLLATION, TRANSLATION, DOMAIN.
   </para>

   <para>
    The TRIGGER privilege was introduced in SQL99.  The RULE privilege
    is a PostgreSQL extension.
   </para>
  </refsect2>

 </refsect1>


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

  <simpara>
   <xref linkend="sql-revoke">
  </simpara>
 </refsect1>

</refentry>

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