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postgresql
4th chunk of `doc/src/sgml/ref/delete.sgml`
58330f1214d1470472cd6cf94427ec7723707bb02648b707000000010000084b
 <command>INSERT</command> or <command>UPDATE</command>
      to be executed instead, the new values may be non-<literal>NULL</literal>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">output_name</replaceable></term>
    <listitem>
     <para>
      A name to use for a returned column.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Outputs</title>

  <para>
   On successful completion, a <command>DELETE</command> command returns a command
   tag of the form
<screen>
DELETE <replaceable class="parameter">count</replaceable>
</screen>
   The <replaceable class="parameter">count</replaceable> is the number
   of rows deleted.  Note that the number may be less than the number of
   rows that matched the <replaceable
   class="parameter">condition</replaceable> when deletes were
   suppressed by a <literal>BEFORE DELETE</literal> trigger.  If <replaceable
   class="parameter">count</replaceable> is 0, no rows were deleted by
   the query (this is not considered an error).
  </para>

  <para>
   If the <command>DELETE</command> command contains a <literal>RETURNING</literal>
   clause, the result will be similar to that of a <command>SELECT</command>
   statement containing the columns and values defined in the
   <literal>RETURNING</literal> list, computed over the row(s) deleted by the
   command.
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   <productname>PostgreSQL</productname> lets you reference columns of
   other tables in the <literal>WHERE</literal> condition by specifying the
   other tables in the <literal>USING</literal> clause.  For example,
   to delete all films produced by a given producer, one can do:
<programlisting>
DELETE FROM films USING producers
  WHERE producer_id = producers.id AND producers.name = 'foo';
</programlisting>
   What is essentially happening here is a join between <structname>films</structname>
   and <structname>producers</structname>, with all successfully joined
   <structname>films</structname> rows being marked
Title: DELETE Command Outputs and Notes
Summary
This section details the output of a successful DELETE command, which includes a command tag showing the number of rows deleted. The count might be less than the matching rows if triggers suppress deletions. A RETURNING clause provides results like a SELECT statement. The section also covers a note on referencing columns from other tables in the WHERE condition using the USING clause, effectively performing a join.