SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 4)
    Identifier a
    Identifier b
    Identifier x
    Identifier y
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 3)
          ExpressionList (children 4)
           Identifier a
           Identifier b
           Literal UInt64_1 (alias x)
           Literal UInt64_2 (alias y)
          TablesInSelectQuery (children 1)
           TablesInSelectQueryElement (children 1)
            TableExpression (children 1)
             TableIdentifier t_dio
          ExpressionList (children 1)
           OrderByElement (children 1)
            Identifier a
   ExpressionList (children 2)
    OrderByElement (children 1)
     Identifier a
    OrderByElement (children 1)
     Identifier b
