SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 3)
    Identifier a
    Literal UInt64_1 (alias x)
    Literal UInt64_2 (alias y)
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier distinct_in_order
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier a
