When you delete the rows of a supertable, the scope of the delete is a supertable and its subtables. Suppose you create a supertable person that has two subtables employee and sales_rep defined under it. The following DELETE statement on the person table can delete rows from all the tables person, employee, and sales_rep:
DELETE FROM person WHERE name ='Walker'
To limit a delete to rows of the supertable only, you must use the ONLY keyword in the DELETE statement. For example, the following statement deletes rows of the person table only:
DELETE FROM ONLY(person) WHERE name ='Walker'