SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 2)
    Function ifNull (alias res) (children 1)
     ExpressionList (children 2)
      Literal \'x\'
      Literal \'y\'
    Function toTypeName (children 1)
     ExpressionList (children 1)
      Identifier res
