Query to find employee of the month in year

Question

HI,
Can anyone please help me in writing the following queries on Northwind database.
1.We are going to motivate employees by creating 'Employee of Month' (employee who has made highest sale). Create Employee of Month List for year 1997. 
2.We want to know how our products’ sales differ from each month. Get the list product which
we sold the most and which we sold the least in quantity for each month of 1997.

Answer 1

And for the second problem try:
WITH cte
AS (
SELECT OD.ProductID
,SUM(OD.Quantity) AS SoldQty
,datepart(month, O.OrderDate) AS MonthNumber
,datename(month, O.OrderDate) AS [Month Name]
FROM dbo.Orders O
INNER JOIN dbo.[Order Details] OD ON O.OrderID = OD.OrderID
WHERE O.OrderDate >= '19970101'
AND O.OrderDate < '19980101'
GROUP BY datepart(month, O.OrderDate)
,datename(month, O.OrderDate)
,OD.ProductID
,cte1
AS (
SELECT P.ProductName
,P.ProductID
,cte.SoldQty
,cte.MonthNumber
,cte.[Month Name]
,ROW_NUMBER() OVER (
PARTITION BY cte.MonthNumber ORDER BY SoldQty
) AS RnMin
,ROW_NUMBER() OVER (
PARTITION BY cte.MonthNumber ORDER BY SoldQty DESC
) AS RnMax
FROM cte
INNER JOIN dbo.Products P ON cte.ProductID = P.ProductID
SELECT [Month Name]
,MIN(CASE
WHEN RnMin = 1
THEN ProductName
END) AS [Least Sold Product]
,MIN(CASE
WHEN RnMin = 1
THEN SoldQty
END) AS [Least Sold Qty]
,MIN(CASE
WHEN RnMax = 1
THEN ProductName
END) AS [Best Sold Product]
,MIN(CASE
WHEN RnMax = 1
THEN SoldQty
END) AS [Best Sold Qty]
FROM cte1
GROUP BY [MonthNumber]
,[Month Name]
ORDER BY [MonthNumber]
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