Most recent record in a left join

Question

Imagine I have the following 3 tables in SqlServer:

Customer (CustomerID, FirstName, LastName)
Address (AddressID, CustomerID, Line1, City, State)
Product (P         


        

Answer 1

Try this:

SELECT a.State, count(c.CustomerID)
FROM Product p
INNER JOIN Customer c ON c.CustomerID = p.CustomerID
LEFT JOIN Address a ON a.CustomerID = c.CustomerID 
      AND a.AddressID = 
        (
           SELECT MAX(AddressID) 
           FROM Address z 
           WHERE z.CustomerID = a.CustomerID
        )
WHERE p.ProductID = 101
GROUP BY a.State