Many web apps that are used for CRUD activities (INSERT, UPDATE and DELETE statements) employ tables that simply have what is often referred to as a manufactured key. Most people more commonly know this as an auto-increment or auto-numbered identity style of primary key and it is typically stored as a data type that's an integer of some sort. This is great until you're working on something a bit bigger, say a business app, and you want the key to a subsidiary table to hold meaning to the end user throughout the app. Perhaps you're setting up location codes or category codes for instance, the value 5 will probably not mean a lot to an end user when filtering inventory reports by location code and it unfortunately forces the user to perform mental lookups to remember that 5 truly means a location of 'Chicago'.

So let's say that you make the decision to structure lookup tables using user defined key values - would you know how to use CF to help maintain referential integrity in your database while not endlessly frustrating your end users?

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