How to average/sum data in a day in SQL Server 200

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 ROASTER_FEED
ORDER timestamp

Data:

timestamp               Feed    
02/07/2011 12:00:01     1246   
02/07/2011 12:00:01     1234    
02/07/2011 12:00:01     1387    
02/07/2011 12:00:02     1425   
02/07/2011 12:00:03     1263   
...    
02/07/2011 11:00:01     1153    
02/07/2011 11:00:01     1348    
02/07/2011 11:00:01     1387    
02/07/2011 11:00:02     1425    
02/07/2011 11:00:03     1223    
....   
03/07/2011 12:00:01     1226    
03/07/2011 12:00:01     1245    
03/07/2011 12:00:01     1384    
03/07/2011 12:00:02     1225    
03/07/2011 12:00:03     1363

I don't know how to average the feed when someone select a date in a month and it give display the average/sum of that day only.

For example, in the outcome, if I select day as 02/07/2011. It would give me something like this:

02/07/2011 1234 (average value/or sum)

Answer 1

Well I'm not a SQL guy, but I'd expect something like:

SELECT SUM(ValueColumn) AS Total, AVG(ValueColumn) AS Average FROM YourTableName
WHERE RecordedTime >= @StartTime AND RecordedTime < @EndTime

(where @StartTime and @EndTime are parameters filled in by the calling code).

(It's not clear to me what will happen if no records are found... worth checking out.)

Answer 2

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 3

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'

Answer 4

Check out some of the tutorials from here http://www.smallsql.de/doc/sql-functions/date-time/index.html ive been looking for something simialr and found that site useful and thought it may help

Answer 5

try this:

SELECT timestamp, sum(FEED)
FROM ROASTER_FEED
WHERE timestamp=....
GROUP BY timestamp

it could be slow if you are handling alot of data, in this case you should considering an additional table which holds the pre-calculated values for each day.

Answer 6

@marc_s hit upon the preferred solution of using a computed columns to handle this but to do it on-the-fly, cast your timestamp data to shear off the time component. In my example, I cast it to a 10 character field that contains the 0 padded date.

;
WITH ROASTER_FEED ([timestamp],[Feed]) AS
(
SELECT CAST('02/07/2011 12:00:01' AS datetime),1246   
UNION ALL SELECT '02/07/2011 12:00:01',1234    
UNION ALL SELECT '02/07/2011 12:00:01',1387    
UNION ALL SELECT '02/07/2011 12:00:02',1425   
UNION ALL SELECT '02/07/2011 12:00:03',1263   

UNION ALL SELECT '02/07/2011 11:00:01',1153    
UNION ALL SELECT '02/07/2011 11:00:01',1348    
UNION ALL SELECT '02/07/2011 11:00:01',1387    
UNION ALL SELECT '02/07/2011 11:00:02',1425    
UNION ALL SELECT '02/07/2011 11:00:03',1223    

UNION ALL SELECT '03/07/2011 12:00:01',1226    
UNION ALL SELECT '03/07/2011 12:00:01',1245    
UNION ALL SELECT '03/07/2011 12:00:01',1384    
UNION ALL SELECT '03/07/2011 12:00:02',1225    
UNION ALL SELECT '03/07/2011 12:00:03',1363
)
SELECT
    -- Shear off the time value by forcing the date into date values
    -- If this was SQL Server 2008+, we'd just cast to date type and
    -- be done with it
    -- Chart for convert options
    -- http://msdn.microsoft.com/en-us/library/ms187928.aspx
    CONVERT(char(10), RF.[timestamp], 121) AS [timestamp]
,   COUNT(1) AS row_counts
,   SUM(RF.Feed) as ValuesSum 
,   AVG(RF.Feed) as Average
FROM 
    ROASTER_FEED RF
GROUP BY
    CONVERT(char(10), RF.[timestamp], 121)    

Results in

timestamp   row_counts   ValuesSum  Average
2011-02-07  10           13091      1309
2011-03-07  5            6443       1288