Let's imagine two SharePoint lists: - Products - Categories In this scenario, the Products list contains a lookup column called Category pointing on the Categories list. Now, I want to write a CAML query to get all the products list items related to the Hardware category. The first thing coming into my mind is the following piece of code: private SPListItemCollection GetProductsByCategory( SPFieldLookupValue Category) { SPList listProducts = this ._web.Lists[ "Products" ]; SPQuery camlQuery = new SPQuery (); camlQuery.Query = string .Format( "<Where><Eq><FieldRef Name=\"Category\" /><Value Type=\"Lookup\">{0}</Value></Eq></Where>" , Category.LookupValue); return listProducts.GetItems(camlQuery); } The problem with this query appears if some categories have the same name ( Hardware ). It's due to the fact that the query doesn't use the