Some time ago , i attended a training course and got chatting to a fellow learner, who was talking about ISNULL.
For a while i was thinking he was saying IS NULL, which confused me , but he explained the difference and , if like me , you never got round to readingthat part of the manual, you'll find it quite usefull.
ISNULL effectively is a nicelittle command that tells SQL server .... "If this vaue is null, then replace it with another value"
whereas...
IS NULL is a comparison for any values that are NULL.
THE ISNULL statement is particularly usefull for when you've got data that hasn't been filled in or collected and yet is displayed in a report to an end user.