Getting clusters of rows close together in time
- by Mike
I have a table basically like so
   ID   |  ItemID  |       Start        |         End        |
---------------------------------------------------------------
    1       234      10/20/09 8:34:22      10/20/09 8:35:10
    2       274      10/20/09 8:35:30      10/20/09 8:36:27
    3       272      10/21/09 12:15:00     10/21/09 12:17:00
    4       112      10/21/09 12:20:14     10/21/09 12:21:21
    5       15       10/21/09 12:22:39     10/21/09 12:24:15
There are two "clusters" of entries here, 1-2 and 3-5 separated by a gap in time, specifically  30 minutes is what I'm interested in. 
What I would like is the first and last rows of the cluster of entries. This is fairly easy to achieve by retrieving all the rows and looping through them in order of start time, but I'd like to have it in SQL if possible. 
I'm using SQL Server 2008, thanks.