Have you tried using that command? What happened for you?
Familiarize your self with Chapter 21 in the Uer's Guide and visit the TSL help file and look at the ddt_* commands.
Once you go thorugh those and do some trial and error runs for yourself, let us know how it goes.
You also might want to read the FAQs on this site as you seemed to miss the one where the title of your posts should reference what you are asking inside. I only visited this thread initially as I thougth it was realting to a database query - boy was I surprised!