Comparing two datasets

Question

Hello, I am trying to write a webservice to compare 2 datasets, one recieved from a client, and the other taken from a database on the webserver. Sofar, I have had little success in accomplishing that, but that may be due to the fact that I'm a relative newbie on C# :-) Does anybody have a clue, a hint, or maybe even some sample code? Thanks in advance