SQL Group BY, Top N Items for each Group

Question

I have a SQL Query which gets gets top 5 sold items at a given store.

SELECT TOP 5 S.UPCCode, SUM(TotalDollarSales) FROM Sales S
WHERE S.StoreId = 1
GROUP BY S.UPCCode
ORDER BY SUM(S.TotalDollarSales) desc

The Sales table has -> UPCCode, SaleDate, StoreId, TotalDollarSales

I am looking for a query which will return me Top 5 items sold for each of the stores in a single query. I can write multiple queries and use a union but it doesn't seem efficient.

How can I get the top 5 sold items for each store in a single query.

Thanks in advance.

Answer 1

;WITH s AS 
(
  SELECT StoreID, UPCCode, tds, rn = ROW_NUMBER()
  OVER (PARTITION BY StoreID ORDER BY tds DESC)
  FROM 
  (
    SELECT StoreID, UPCCode, tds = SUM(TotalDollarSales)
    FROM Sales
    GROUP BY StoreID, UPCCode
  ) AS s2
)
SELECT StoreID, UPCCode, TotalDollarSales = tds
FROM s
WHERE rn <= 5
ORDER BY StoreID, TotalDollarSales DESC;

Answer 2

try this:

select ss.StoreId,is.*
from (select distinct StoreId from Sales) ss
cross apply (SELECT TOP 5 S.UPCCode, SUM(TotalDollarSales) as SumTotalDollarSales FROM Sales S
             WHERE S.StoreId = ss.StoreId
             GROUP BY S.UPCCode
             ORDER BY SUM(S.TotalDollarSales) desc) is