title: sql query selection
body: <p>I am trying to build a query which will do this: 
  Lets say for example I have 100 records in the table. I have .net form which calls the query. I have a querystring parameter pageindex, something like <a href="http://mysite.com?id=2" rel="nofollow">http://mysite.com?id=2</a>. 
  What I want to do now is if id = NULL, then get the 1st set of records from that table whichave id of 1 to 20, means from 1 to 20, if id=2 then get the 2nd set of recordw, from row 20 to 40, if id=3 then get the 3rd set of records, meaning records from 40 to 60, from that table.<br>
  I want to know if this is possible. 
  Thanks a lot in advance, Laziale</p>