The child table is either referenced in a correlated subquery that is part of a DELETE or MERGE statement or as a source table in a MERGE statement. The child table cannot be one of the tables on which a delete would cascade. These actions are not allowed because the result depends on the order in which the rows are processed. Rewrite your query so that the child table is not referenced in a correlated subquery, or as source table of the MERGE statement, or both.