shoe_ready.total_avail &gt;= 2;</PRE
><P>

    Similarly, the rules for <TT
CLASS="LITERAL"
>shoe</TT
> and
    <TT
CLASS="LITERAL"
>shoelace</TT
> are substituted into the range table of
    the subquery, leading to a three-level final query tree:

</P><PRE
CLASS="PROGRAMLISTING"
>SELECT shoe_ready.shoename, shoe_ready.sh_avail,
       shoe_ready.sl_name, shoe_ready.sl_avail,
       shoe_ready.total_avail
  FROM (SELECT rsh.shoename,
               rsh.sh_avail,
               rsl.sl_name,
               r