Frequently, and for general ease-of-use reasons mostly.

Say for (a very simple) example you have FirstName and LastName columns, and often need to produce a results set that contains a FullName field of the format FirstName + ' ' + LastName.

You can either:

- Use a view, but that has the disadvantage that you need to rewrite all queries to use the view instead of the table.

- Do it in the select statement each time you need the FullName, but that has the disadvantage that you might have to repeat code in lots of places.

- Create the FullName column and keep it populated with a trigger on the other two columns, but that has an overhead for INSERTs and UPDATEs and perhaps a little for management.

- Use a computed column. Doesn't affect any existing queries, doesn't affect inserts or updates (unless persisted I think, but that's another story) and is a one-time-only operation to set up.

- There may be yet other alternatives of course, but I can't think what they might be off the top of my head.

Horses for courses as they say.

Duncan