SQL question

HI everyone!

I have 3 tables

1. customer (customer_id,name,address) primary key = customer_id
2. account (account_number,balance) primary key =account_number
3. depositor (account_number,customer_id,deposite_date)

depositor is many to many relation between customer & account

Now i want to delete customers who has account balance less than 500.00.

I tried following SQL. It work nice if there is only one customer satisfied the condition.
If more than one customer has account balance less than 500 this didn't work.
It says single row sub query returns multiple row.

here is my sql code

delete from customer
where
customer_id=
(
 select

     distinct customer_id
 from

     customer c join depositor d using(customer_id) join account a using(account_number)
 where

     a.balance<500
);

Please help me.
What should i do? Received on Sun Apr 23 2006 - 23:07:26 CDT