SQL does not allow <str> on streams with multiple relations

  Explanation:  You have used MODIFY or ERASE on  a  stream  whose
  record  selection  expression  references more than one relation
  (i.e, contains a CROSS clause).  SQL only permits its equivalent
  of  MODIFY  (UPDATE)  and  ERASE  (DELETE) to operate on streams
  which  reference  no  more  than  one  relation  as  these   are
  considered read only.

  User Action:  Rewrite your code so it does not attempt to modify
  or erase from these relations.