MSSQL query range for a day over a month - sql

Question

I am trying to retrieve the range for the value field over each 24hr period over a predefined time period. The issue is that the time period is between 7am and 7am the next day. (not a daily figure)
For example, I would like the range for day 1, then range for day 2, etc. I've tried using the below query but the production field keeps coming back with the same data, could anyone please shed some light on how I can make this work?
Thank you very much.
select tagname, convert(date,datetime),
(
select (max(Value)-min(Value)) as Range
from Runtime.dbo.AnalogHistory
where (TagName = 'LS_CV004_WX1_PROD_DATA.Actual_Input')
and DateTime BETWEEN dateadd(hh,7,convert(datetime,convert(date,datetime))) AND dateadd(hh,31,convert(datetime,convert(date,datetime)))
) as Production
from runtime.dbo.analoghistory
where (TagName = 'LS_CV004_WX1_PROD_DATA.Actual_Input')
and datetime between '20151101' and '20151201'
group by tagname, convert(date,DateTime)
I would like to result to be as per below
tagname | date | production

Answer 1

Below is one method that uses CTEs to generate a row for each date in the specified range, and then joins to the table on the date plus a 7 hour offset. Consider creating a utility calendar table for this type of task.
DECLARE
#StartDate date = '20151101'
, #EndDate date = '20151201';
WITH
t8 AS (SELECT n FROM (VALUES(0),(0),(0),(0),(0),(0),(0),(0)) t(n))
, t512 AS (SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) - 1 AS num FROM t8 AS a CROSS JOIN t8 AS b CROSS JOIN t8 AS c)
, dates AS (SELECT DATEADD(day, num, #StartDate) AS Date FROM t512 WHERE num <= DATEDIFF(day, #StartDate, #EndDate))
SELECT TagName, Date, MAX(Value)-MIN(Value) as Production
FROM dates
JOIN dbo.AnalogHistory ON
AnalogHistory.DateTime >= DATEADD(hour, 7, Date)
AND AnalogHistory.DateTime < DATEADD(hour, 31, Date)
GROUP BY TagName, Date
ORDER BY TagName, Date;

Answer 2

Your subquery is not correlated to the outer query, so it is no surprise that it returns the same value. I think you want something like this:
select tagname, convert(date, datetime),
(select (max(ah2.Value) - min(ah2.Value)) as Range
from Runtime.dbo.AnalogHistory ah2
where ah2.TagName = 'LS_CV004_WX1_PROD_DATA.Actual_Input' and
ah2.DateTime BETWEEN dateadd(hour, 7, convert(datetime, convert(date, ah.datetime))) AND
dateadd(hour, 31, convert(datetime, convert(date, ah.datetime)))
) as Production
from runtime.dbo.analoghistory ah
where TagName = 'LS_CV004_WX1_PROD_DATA.Actual_Input' and
datetime between '20151101' and '20151201'
group by tagname, convert(date, DateTime);
Note the use of ah2 and ah in the subquery.