Exists Operator

Question

Hi everyone,
I have a problem with the NOT EXISTS operator in oracle.
I have 3 tables.
Customer(cust_id, cust_name)
Truck(truck_id,driver)
Shipment(shipment_id,cust_id,truck_id)
truck_id and cust_id are foreign keys in shipment table. I have to
List all customers who have shipments delivered by "every" truck using EXISTS operator.
Any help is greatly appreciated.
Thanks in advance.
Regds,
Beulah

Answer 1

Try this:
select *
from customer c
where exists (select 'x'
from shipment s
where s.cust_id = c.cust_id
group by s.cust_id
having count(distinct s.truck_id) = (select count(truck_id) from truck)
I tried it with following data:
create table Customer(cust_id number , cust_name varchar2(50));
create table Truck(truck_id number ,driver varchar2(50));
create table Shipment(shipment_id number ,cust_id number ,truck_id number);
insert into customer values (1, 'CUST1');
insert into customer values (2, 'CUST2');
insert into customer values (3, 'CUST3');
insert into truck values (10, 'DRV1');
insert into truck values (20, 'DRV2');
insert into truck values (30, 'DRV3');
insert into shipment values(100,1,10);
insert into shipment values(101,1,20);
insert into shipment values(102,1,30);
insert into shipment values(104,2,20);
insert into shipment values(105,2,30);
insert into shipment values(106,2,20);
result:
CUST_ID CUST_NAME
1 CUST1