select-expr =

  -+-+->  select-clause  ------------+-+------+
   | +-> ( select-expr )  -----------+ |      |
   | +->   TABLE table-ref ----------+ |      |
   +------ select-merge-clause <-------+      |
     +------------------- <-------------------+
     +-+--------------------+--+------------------+--+--------------------+->
       +-> order-by-clause -+  +-> offset-clause -+  +-> limit-to-clause -+

  select-merge-clause =

  -+-> EXCEPT -+--------------+---+----+-------------------+-->
   |           +-> DISTINCT --+   |    +-> CORRESPONDING --+
   +-> INTERSECT -+-------------+-+    +-> NATURAL --------+
   |              +-> DISTINCT -+ |
   +-> MINUS ---------------------+
   +-> UNION --+-------------+----+
               +-> ALL ------+
               +-> DISTINCT -+

  select-clause =

  SELECT -+-------------+-> select-list -------------------------------+
          +-> ALL ------+                                              |
          +-> DISTINCT -+                                              |
  +------------------<-------------------------------------------------+
  +-> FROM -+--> table-ref --+-----------------------------------------+
            +------ , <------+                                         |
  +--------------------------------------------------------------------+
  ++--------->-----------------------+-+------------->----------------++
   +> WHERE predicate ---------------+ +> GROUP BY -+> <column-name> -+|
                                                    +> value-expr ----+|
                                                    +------- ,<-------+|
  +--------------------------------------<-----------------------------+
  ++---------->----------+---------------------------------------------->
   +-> HAVING predicate -+

  select-list =

  -+-+----> * ------------------------------------------------------+-+->
   | +-+--> value-expr --+--------------------------------------+-+-+ |
   |   |                 +-> AS <name> -+----------------------++ |   |
   |   |                                +-> edit-using-clause -+  |   |
   |   |                                                          |   |
   |   ++-> <table-name> ------+-> . * ---------------------------+   |
   |    +-> <view-name> -------+                                      |
   |    +-> <correlation-name> +                                      |
   +---------------- , <----------------------------------------------+

  edit-using-clause =

  --> EDIT USING -+-> edit-string ---+->
                  +-> <domain-name> -+

  table-ref =

  --+--> <table-name> --+--+-----------------------------+-->
    +--> <view-name>  --+  +-> correlation-name-clause --+
    +--> derived-table -+                                |
    +--> joined-table -----------------------------------+

  derived-table =

  ----> ( -+-> select-expr --+-> ) ---->
           +-> joined-table -+

  joined-table =

  --+-------> qualified-join ------+---->
    +-------> cross-join ----------+
    +-> ( --> joined-table --> ) --+

  qualified-join =

  -+-> table-ref -+-------------+--> JOIN --> table-ref -+
   |              +> join-type -+                        |
   | +---------------------------------------------------+
   | ++-> ON predicate -------------------------------+-----------+>
   |  +-> USING ----> ( -+> <column-name> +-> ) ------+           |
   |                     +------ , <------+                       |
   +-> table-ref -> NATURAL -+-------------+-> JOIN -> table-ref -+
                             +> join-type -+

  cross-join =

  ---> table-ref --> CROSS JOIN --> table-ref --->

  join-type =

  --+-> INNER ------------------+-->
    +-> LEFT ---+--> OUTER -----+
    +-> RIGHT --+
    +-> FULL ---+

  correlation-name-clause =

  -> AS <correlation-name> +------------------------------------+->
                           +-> ( -+-> <name-of-column> -+-> ) --+
                                  +-------- , <---------+

  order-by-clause =

  --> ORDER BY -++-> value-expr   -++---------+-+-->
                |+-> <integer> ----++-> ASC --+ |
                |                   +-> DESC -+ |
                +------------ , <---------------+

  offset-clause =

  ---> OFFSET skip-expression -+-> ROW  --+-->
                               +-> ROWS --+

  limit-to-clause =

  -+> LIMIT TO -+-> limit-expression -+---------------------------+++---------++>
   |            |                     +-> OFFSET skip-expression -+|+-> ROW  -+|
   |            |                     +-> SKIP skip-expression  --+|+-> ROWS -+|
   |            +-> skip-expression , limit-expression  -----------+           |
   |                                                                           |
   +> FETCH -+> FIRST -+--+---------------------+--+----------+-> ONLY --------+
             +> NEXT --+  +-> limit-expression -+  +-> ROW  --+
                                                   +-> ROWS  -+

  optimize-clause =

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