SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Identifier NewColumn
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier test_a
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      Subquery (alias s) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 2)
          ExpressionList (children 2)
           Identifier OldColumn
           Identifier NewColumn
          TablesInSelectQuery (children 1)
           TablesInSelectQueryElement (children 1)
            TableExpression (children 1)
             TableIdentifier test_b
     TableJoin (children 1)
      ExpressionList (children 1)
       Identifier OldColumn
   Function notEquals (children 1)
    ExpressionList (children 2)
     Identifier NewColumn
     Literal \'\'