SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 5)
    Identifier t.a.size0
    Identifier t.a.null
    Identifier t.u
    Identifier t.s
    Identifier t.s.null
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier subcolumns