Top 3 rows per country - sql

Question

I've produced a report of "Which and how many of Products been sold in each country". I'm using Northwind database, SQL Server 2012.
The following is the code:
SELECT
o.ShipCountry AS 'Country',od.ProductID,
p.ProductName, p.UnitPrice,
SUM(od.Quantity) AS 'Number of Units Sold'
FROM
Products p
INNER JOIN
[Order Details] od ON od.ProductID = p.ProductID
INNER JOIN
Orders o ON o.OrderID = od.OrderID
GROUP BY
p.ProductName, od.ProductID, p.UnitPrice, o.ShipCountry
ORDER BY
o.ShipCountry, 'Number of Units Sold' DESC
The result shows over 900 rows, each country has about 10 to 20 rows:
But I want to take it up a notch, and now I want to produce "Top 3 products sold per country"
So I tried ROW_NUMBER() OVER (PARTITION BY but I'm clumsy at using Row_NUMBER()
The below is my wrong code:
WITH CTE AS
(
SELECT
o.ShipCountry AS 'Country',od.ProductID,
p.ProductName, p.UnitPrice,
SUM(od.Quantity) AS 'Number of Units Sold',
ROW_NUMBER() OVER (PARTITION BY o.ShipCountry ORDER BY ('Number of Units Sold') DESC) AS 'Number of Units Sold'
FROM
Products p
INNER JOIN
[Order Details] od ON od.ProductID = p.ProductID
INNER JOIN
Orders o ON o.OrderID = od.OrderID)
SELECT
'Country', ProductID,
ProductName, UnitPrice, 'Number of Units Sold'
FROM
CTE
WHERE
'Number of Units Sold' < 4
GROUP BY
p.ProductName, od.ProductID, p.UnitPrice, o.ShipCountry
ORDER BY
o.ShipCountry DESC

Answer 1

Try this:
WITH CTE AS
(
SELECT
o.ShipCountry, od.ProductID,
p.ProductName, p.UnitPrice,
SUM(od.Quantity) AS UnitsSold,
RowNum = ROW_NUMBER() OVER (PARTITION BY o.ShipCountry ORDER BY SUM(od.Quantity) DESC)
FROM
Products p
INNER JOIN
[Order Details] od ON od.ProductID = p.ProductID
INNER JOIN
Orders o ON o.OrderID = od.OrderID
GROUP BY
p.ProductName, od.ProductID, p.UnitPrice, o.ShipCountry
)
SELECT *
FROM CTE
WHERE CTE.RowNum <= 3
Basically, in the CTE, you define the columns you want - word of caution: don't use column names with spaces and stuff like that! Makes for a nice presentation on screen, but really hard to use in a query!
Then you add the ROW_NUMBER() that will number each entry for each country starting at 1.
And finally, you select from the CTE, and you take only those rows with a RowNum <= 3 ==> the TOP 3 for each country.

Answer 2

;with CTE as(
SELECT o.ShipCountry AS 'Country',
od.ProductID,
p.ProductName,
p.UnitPrice,
SUM(od.Quantity) AS 'Number of Units Sold'
FROM Products p
INNER JOIN [Order Details] od
ON od.ProductID=p.ProductID
INNER JOIN Orders o
ON o.OrderID=od.OrderID
GROUP BY p.ProductName, od.ProductID, p.UnitPrice, o.ShipCountry
)
,CTE2 as
( Select
CTE.Country,
CTE.ProductID,
CTE.ProductName,
CTE.UnitPrice,
CTE.[Number of Units Sold],
ROW_NUMBER() OVER (PARTITION BY CTE.Country
ORDER BY CTE.[Number of Units Sold] DESC) AS rownum
from CTE
)
select CTE2.Country,
CTE2.ProductID,
CTE2.ProductName,
CTE2.UnitPrice,
CTE2.[Number of Units Sold]
FROM CTE2
WHERE CTE2.rownum<4
ORDER BY CTE2.Country, CTE2.[Number of Units Sold] DESC

Answer 3

Try this :
SELECT Country, ProductID,
ProductName,UnitPrice,Number_of_Units_Sold
FROM
(
SELECT o.ShipCountry AS Country, od.ProductID as ProductID,
p.ProductName as ProductName, p.UnitPrice as UnitPrice,
SUM(od.Quantity) AS Number_of_Units_Sold,
ROW_NUMBER() OVER (PARTITION BY o.ShipCountry ORDER BY (SUM(od.Quantity)) DESC) AS MYRANK
FROM Products p
INNER JOIN [OrderDetails] od
ON od.ProductID=p.ProductID
INNER JOIN Orders o
ON o.OrderID=od.OrderID
GROUP BY o.ShipCountry, p.ProductName, od.ProductID, p.UnitPrice, o.ShipCountry
) tmp
where MYRANK <= 3
ORDER BY Country, Number_of_Units_Sold DESC