T-SQL Multiple grouping

Question

I have follwing data :

Product Price   StartDate                   EndDate
Apples  4.9     2010-03-01 00:00:00.000     2010-03-01 00:00:00.000
Apples  4.9           


        

Answer 1

I believe this is the best-performing solution so far:

WITH Calc AS (
   SELECT *,
      Grp = DateAdd(day, -Row_Number()
         OVER (PARTITION BY Product, Price ORDER BY StartDate), StartDate
      )
   FROM dbo.PriceHistory
)
SELECT Product, Price, FromDate = Min(StartDate), ToDate = Max(StartDate)
FROM Calc
GROUP BY Product, Price, Grp
ORDER BY FromDate;

Try this out yourself