Question

I have 3 tables.
cinema, booking and customer

create table cinema
(
c_id int,
location varchar(10)
)
insert into cinema values(1,'New York');
insert into cinema values(2,'London');
insert into cinema values(3,'Paris');

create table booking
(
c_id int,
cust_id int
)

insert into booking values(1,10);
insert into booking values(2,11);
insert into booking values(3,12);
insert into booking values(3,13);
insert into booking values(2,14);

create table customer
(
cust_id int,
cust_name varchar(10)
)

insert into customer values(10,'sam');
insert into customer values(11,'adrian');
insert into customer values(12,'mark');
insert into customer values(13,'jim');
insert into customer values(14,'tom');

I want to select customer id(ie; cust_id), customer name(cust_name) and location(from cinema table) of all customer who have not booked in paris.

what i want is —

cust_id cust_name location
10      sam       New York   
11      adrian    London
14      tom       London

I tried a lot….
one of my code is —

SELECT customer.cust_id,customer.cust_name,
cinema.location as Location FROM booking,cinema,customer
WHERE booking.c_id=cinema.c_id AND location!='Paris';

it gives me 15 result..
I cant think how to do this..
please help me with this.

Answer 1

In your code you’re not joining booking to customer, which is causing your problem. I use explicit joins as opposed to implicit here. Though there is no difference, the explicit syntax is standard.

select cu.cust_id, cu.cust_name, ci.location
  from cinema ci
  join booking b
    on ci.c_id = b.c_id
  join customer cu
    on b.cust_id = cu.cust_id
 where ci.location <> 'Paris'

I’m not entirely certain about the structure of your booking table. I would expect a few more columns, for instance number of tickets, etc.