Description of the illustration group_by_clause.eps

  [ HAVING condition ]GROUP BY 
  ( ( (
  expr | c_alias | position 
  | rollup_cube_clause 
  | grouping_sets_clause) 
  [ , ( expr | c_alias | position 
  | rollup_cube_clause 
  | grouping_sets_clause) ...]
  )
  | ALL
  )
    [ HAVING condition ]