CustomerID's Where The ProductID Exists In Both (was SQL Help)

Could you provide a link to an SQL tutorial site?

Also, Id hate to make a new thread, 3 in one day on stupid newbie questions isnt good for the self-esteem, how do I use the group by here?


Code:


SELECT C.customerID, productID FROM [order details] OD
INNER JOIN Orders O
ON O.orderID = OD.orderID
INNER JOIN customers C
ON C.customerID = O.customerID
WHERE productID in (56,59)
ORDER BY C.customerID



and then get only the customerID's where the productID exists in both? These are questions from an old SQL exam I got. Just practising because Im interested in becoming a DB specialist, Im obviously a long way off, but if I get the basics dialed then my coarse will fly by me and Ill get my certific quick! Instead of wasting money on getting a tutor, or going to college.