A subquery in an INSERT, UPDATE or DELETE statement referenced
  the subject table

  Explanation:  You tried to use the same table in an INSERT,
  UPDATE or DELETE statement both as the target and in a subquery.
  The current ANSI and ISO SQL standards do not permit this.

  User Action:  If it is important to use only standard features
  in your program, you should remove the subquery which references
  the subject table.