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)
7:40am is 460 minutes after 00:00
7:40pm is 1180 minutes after 00:00
midnigth is 1440 minutes after 00:00
And DATEPART(hh, SomeDate)*60 + DATEPART(mi, SomeDate) gives you the amount of minutes after 00:00 for a given SomeDate
So, you could use:
SELECT
AVG(Temperature) As Dayshift
FROM Drye_data
WHERE DATEPART(hh, TimeStamp)*60 + DATEPART(mi, TimeStamp) BETWEEN 460 AND 1180
AND @SelectedDate = CAST(FLOOR(CAST(TimeStamp AS FLOAT)) AS DATETIME)
and for the Nightshift:
SELECT
AVG(Temperature) As Nigthshift
FROM Drye_data
WHERE (
(DATEPART(hh, TimeStamp)*60 + DATEPART(mi, TimeStamp) BETWEEN 0 AND 460)
AND @SelectedDate = DATEADD(dd, 1, CAST(FLOOR(CAST(TimeStamp AS FLOAT)) AS DATETIME))
)
OR
(
(DATEPART(hh, TimeStamp)*60 + DATEPART(mi, TimeStamp) BETWEEN 1180 AND 1440) AND @SelectedDate = CAST(FLOOR(CAST(TimeStamp AS FLOAT)) AS DATETIME)
)
One possibility, if you need to do this often enough: add three computed columns for day, month, year to your table. Those columns are computed automatically based on the timestamp column, and they're just integer values, so they're easy to use in a GROUP BY.
To do this, use these T-SQL statements:
ALTER TABLE dbo.ROASTER_FEED ADD TSDay AS DAY(timestamp) PERSISTED
ALTER TABLE dbo.ROASTER_FEED ADD TSMonth AS MONTH(timestamp) PERSISTED
ALTER TABLE dbo.ROASTER_FEED ADD TSYear AS YEAR(timestamp) PERSISTED
Now, you can easily select your data based on any day you wish:
SELECT TSDay, TSMonth, TSYear, SUM(FEED) -- use AVG(FEED) for average values
FROM dbo.ROASTER_FEED
WHERE TSYear = 2011 AND TSMonth = 8 -- or whatever you want to grab from the table!
ORDER BY timestamp
GROUP BY TSDay, TSMonth, TSYear
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.)
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.
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'
@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
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)
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
来源：https://stackoverflow.com/questions/7450463/how-to-average-sum-data-in-a-day-in-sql-server-2005