Subqueries in Non-SELECT Queries

Subqueries can also be used in UPDATE  and DELETE  statements. Figure  shows two examples.  

        test=> DELETE FROM customer   
        test-> WHERE customer_id NOT IN (
        test(>                           SELECT customer_id
        test(>                           FROM salesorder
        test(>                          );
        DELETE 0
        test=> UPDATE salesorder
        test-> SET    ship_date = '11/16/96'
        test-> WHERE  customer_id = (
        test(>                       SELECT customer_id 
        test(>                       FROM   customer
        test(>                       WHERE  name = 'Fleer Gearworks, Inc.'
        test(>                      );
        UPDATE 1  

The first query deletes all customers with no sales orders. The second query sets the ship_date equal to '11/16/96' for all orders made by Fleer Gearworks, Inc. The numbers after DELETE  and UPDATE  indicate the number of rows affected by the queries.