SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Identifier a.key
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier a
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier b
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Function tuple (children 1)
         ExpressionList (children 1)
          Identifier a.key
        Function tuple (children 1)
         ExpressionList (children 1)
          Identifier b.key
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier a.key
