With SQL Server you can create TVFs (table-valued functions). So long as they are 'inline' (lacking BEGIN and END) they will be inlined into any query that uses

With SQL Server you can create TVFs (table-valued functions). So long as they are 'inline' (lacking BEGIN and END) they will be inlined into any query that uses them. If your SQL fu is up to scratch they are extremely powerful - e.g. CROSS APPLYing them is one of the best ways I've seen to do reusable row-level filtering.