singleton-select =

  SELECT -+-------------+-> select-list --+
          +-> ALL ------+                 |
          +-> DISTINCT -+                 |
    +-------------------------------------+
    +-> into-target -----------------+
    +--------------------------------+
    +> FROM -+--> table-ref -----+-+
             +---------- , <-----+ |
    +------------------------------+
    +> WHERE predicate -+------------->-----------------++
                        +-> GROUP BY -+> <column-name> ++|
                                      +------- , <-----+ |
    +--------------------------<-------------------------+
    ++--------------------+-+-----------------------+----+
     +> HAVING predicate -+ +-> limit-to-clause ----+    |
    +----------------------------------------------------+
    +-+---------------------+-+---------------------+------>
      +> for-update-clause -+ +-> optimize-clause --+

  into-target =
  ----> INTO --+-+-> <parameter> -----------++->
               | +-> <qualified-parameter> -+|
               | +-> <variable> ------------+|
               +------------- , <------------+

  for-update-clause =

  --> FOR UPDATE -+-------------------------+->
                  +-+-> OF <column-name> -+-+
                    +-------- , <---------+

  optimize-clause =

  --+---------------------------------------------------------------+--->
    +-> OPTIMIZE --+-+-> FOR -+-> FAST FIRST --------+----------+-+-+
                   | |        +-> TOTAL TIME --------+          | |
                   | |        +-> SEQUENTIAL ACCESS -+          | |
                   | +-> USING <outline-name> ------------------+ |
                   | +-> WITH -+-> DEFAULT  --+-> SELECTIVITY  -+ |
                   | |         +-> SAMPLED  --+                 | |
                   | |         +-> AGGRESSIVE +                 | |
                   | +-> AS <query-name> -----------------------+ |
                   +---------------- <----------------------------+