SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 1)
   ExpressionList (children 1)
    Function equals (children 1)
     ExpressionList (children 2)
      Function concatWithSeparator (children 1)
       ExpressionList (children 3)
        Literal \'1\'
        Literal \'a\'
        Literal NULL
      Literal NULL
