Sql express time Query - sql

Question

am working with MS SQL express and Ignition SCADA by http://www.inductiveautomation.com/
In the SCADA package you are able to create tags from SQL query's. I am trying to use SQL tags to calculate the average packages per minute in a 30min time frame. I was able to do this with two tags and an expression
SELECT MAX(L8Total)
FROM Slicing_tot
WHERE t_stamp BETWEEN DATEADD(minute, -30, GETDATE()) AND GETDATE()
 
SELECT MIN(L8Total)
FROM Slicing_tot
WHERE t_stamp BETWEEN DATEADD(minute, -30, GETDATE()) AND GETDATE()
What I would like to do from here is store the expressions value and find the max and average for the last 30 days based on time. But I have no idea how to filter 30days of information at a certain time
IE what was the max packages per minute we had at 10:30 from the last 30 days
IE what was the average packages per minute we had at 11:45 form the last 30 days
Please keep in mind that I am new to SQL

Answer 1

SELECT DATEPART(MINUTE, t_stamp)
,MAX(L8Total)
,MIN(L8Total)
FROM Slicing_tot
WHERE ( CONVERT(DATE, t_stamp) >= CONVERT(DATE, GETDATE() - 30)
AND CONVERT(DATE, t_stamp) <= CONVERT(DATE, GETDATE())
)
AND ( CONVERT(TIME, #variable) >= '22:30'
AND CONVERT(TIME, #variable) <= '23:00'
)
GROUP BY DATEPART(MINUTE, t_stamp)
GETDATE()-30 will get you datetime of today minus 30 days ago. Since you are working with datetime field it is best to convert it to date to make sure that you get correct date range. Use of >= and <= is better than between because you is always clear what you doing. Read #Aaron's blog
than for the second part just convert your datetime column to time to limit to specific range during the day.

Answer 2

The following would select between 10 & 11 AM over those 30 days
SELECT MIN(L8Total)
FROM Slicing_tot
WHERE t_stamp BETWEEN DATEADD(dd, -30, GETDATE()) AND GETDATE()
and Datepart(hh,t_stamp) between 10 and 11
or you could compare the time part of the t_stamp to time
SELECT MIN(L8Total)
FROM Slicing_tot
WHERE t_stamp BETWEEN DATEADD(dd, -30, GETDATE()) AND GETDATE()
and convert(time, t_stamp) between '10:30:00.000' and '10:31:00.000'
which would give you the results between 10:30 and 10:31 inclusive of the end points over the last 30 days.