When are computed columns appropriate?

Question

I\'m considering designing a table with a computed column in Microsoft SQL Server 2008. It would be a simple calculation like (ISNULL(colA,(0)) + ISNULL(colB,(0))) - like a tot

Answer 1

Let's say you have a computed column called ProspectRanking that is the result of the evaluation of the values in several columns: ReadingLevel, AnnualIncome, Gender, OwnsBoat, HasPurchasedPremiumGasolineRecently.

Let's also say that many decentralized departments in your large mega-corporation use this data, and they all have their own programmers on staff, but you want the ProspectRanking algorithms to be managed centrally by IT at corporate headquarters, who maintain close communication with the VP of Marketing. Let's also say that the algorithm is frequently tweaked to reflect some changing conditions, like the interest rate or the rate of inflation.

You'd want the computation to be part of the back-end database engine and not in the client consumers of the data, if managing the front-end clients would be like herding cats.

If you can avoid herding cats, do so.