Question

I am trying to recap on my sql skill, now I am trying to run a simple query on northwinddb to show me the top customer for each year, but as soon as I use the TOP function only 1 record gets display no matter on what I partition by, This is my T-SQL code

SELECT DISTINCT TOP 1 C.CompanyName
, YEAR(O.OrderDate) AS Year
, SUM(Quantity) OVER(PARTITION BY C.CompanyName, YEAR(O.OrderDate)) AS Total
FROM Customers C JOIN Orders O
    ON C.CustomerID = O.CustomerID JOIN [Order Details] OD
    ON O.OrderID = OD.OrderID

Answer 1

You can do this bit more compactly in SQL Server 2008 as follows:

select top (1) with ties
  C.CompanyName,
  Year(O.OrderDate) as Yr,
  sum(OD.Quantity) as Total
from Orders as O
join Customers as C on C.CustomerID = O.CustomerID
join "Order Details" as OD on OD.OrderID = O.OrderID
group by C.CompanyName, Year(O.OrderDate)
order by 
  row_number() over (
    partition by Year(O.OrderDate)
    order by sum(OD.Quantity) desc
  );