In a word - you can't.

Well actually that's two words!!

You need to think completely differently about the way you handle data. Think of the SQL Server as a big file server. It doesn't know about what end users are doing with its' data, at the lowest level.

First of all, tell us how you are accessing the data: is it through a view for example? How wide (total width) are your rows? Perhaps using stored procedures would be easier for you to program?

Tell us some more please.

Regards
Simon