You really haven't provided enough information. Please look at the link referring to Jeff Moden in my signature to help us help you. That being said, I assume that since this is a product table, that the productid is the clustered key. Clustered index contains all of your data. So, since you are filtering on SalesID and it is not the first predicate in the clustered key (also assuming you have no other indexes), it has to scan the clustered index (data) to find what you are looking for. One solution (Assuming it makes sense on all levels), is to add a non-clustered index on Product(SalesID, Product) and include the productID column.