Get Data From Last Row Of A Resultset...(SQL 2005)

Hi,
Just when I thought I knew SQL...

I have a stored proc that returns several resultsets to an ASP.NET application. One of these resultsets is sorted by date and I need to access the highest date (i.e. the one on the last row) and store it in a local var in the sproc for use in a separate query. How can I do this? Obviously I want the entire resultset to be returned as usual but I also don't want to execute the same query twice.

e.g.
Original sproc is:
===================================
select id from table
...
select adate from anothertable order by adate
...
select somethingelse from yetanothertable
...
===================================
This normally returns 3 resultsets accessible from ASP.NET.


However I want to get the highest "adate" from that middle query and use it later i.e:
===================================
select id from table
...
declare mydate datetime
select adate from anothertable order by adate (<--somewhere here "mydate" is set to the max date)
...
update somewhere set value = 1 where thedate = mydate
...
select somethingelse from yetanothertable
...
===================================

without changing the data returned to asp.net. Easy? I hope so :-)

Thanks for any help!!