How to average/sum data in a day in SQL Server 2005

Question

I\'m trying to average data in SQL Server 2005 in a day. Here is what my database look like this if I use simple query as

SELECT timestamp, FEED
FROM ROASTE         


        

Answer 1

To get the average feed for one day you can use this.

declare @Date datetime

set @Date = '20110702'

select @Date as [timestamp], avg(FEED) as AvgFeed
from ROASTER_FEED
where [timestamp] >= @Date and 
      [timestamp] < dateadd(day, 1, @Date)

Answer 2

SELECT COUNT(timestamp) as NumValues, 
       SUM(Feed) as ValuesSum, 
       AVG(Feed) as Average

  FROM ROASTER_FEED

 WHERE timestamp BETWEEN '1/1/2011'  AND '9/15/2011'