Pease share Link to download DQL Tester
As far as I remember, it is copyrighted to Xerox Germany (Xerox Global Services) so you'll have to get in touch with them to get it....
I'm not familiar with the DQL Tester, but there are several DQL editors available that allow you to enter DQL, submit it to the Content Server, and receive results. Check out Sampson, RepoInt, Qit, DqMan... there is, of course, one built into Webtop, and one available for D2 (