Obtaining Min/Max for Day Summary Across Midnight

Question

Hi there,
Have a bit of an interesting problem.
I would like summaries in the form of
Date, SESSIONA_Maximum, SESSIONA_Minimum, SESSIONB_Maximum, SESSIONB_Minimum
I have two dimensions, Date and Time. Day represents levels at Day, Week, Month, Qtr, Year. Time is Hour, Minute, Second.
An example of Session A would be that it starts at June 27th at 4:30PM and ends at June 28th 9:30AM. Session B would start at 9:30AM and end at 4:15PM.
As you can see session A starts on one day and ends on the next. And I would like to combine it's summary on the next day since this is when Session B will start and end. How can I go about accomplishing this?
Ideally, I'd like the ability to add another dimension which corresponds to the times of Session A or Session B because I will have many calculations that are the same, but will have to be independently applied to either Session A or Session B. Some will also have to be applied to both.

Answer 1

Since there is some context missing, I don't get everything, but from your narrative, it seems likely you need something like:
WITH CTE AS (
   SELECT keycol,
          period = CASE WHEN Start < '12:00' THEN 'AM'
                        WHEN Start < '17:00' THEN 'PM'
                        ELSE 'EVE'
                   END,
          start, stop
   FROM   tbl
SELECT keycol, period, MIN(start), MAX(stop)
FROM   CTE
GROUP  BY keycol, period
Erland Sommarskog, SQL Server MVP, [email protected]