title: Getting distinct list of ID's in CoreData
body: <p>What's the most efficient way to perform this query on a CoreData table?  To use the standard employees database model -- I want DISTINCT department ID's for all departments that contain employees with job-description "chef."  As it happens, there is only a single table (Employees) relevant here -- I don't actually have a departments table, just department ID's that are repeated.</p>