Web Listing 7: JOIN Query Returning Desired Results
SELECT DISTINCT C.Country, C.Region, C.City
FROM dbo.Customers AS C
  JOIN dbo.Employees AS E
    ON (C.Country = E.Country
        OR (C.Country IS NULL AND E.Country IS NULL))
    AND (C.Region = E.Region
         OR (C.Region IS NULL AND E.Region IS NULL))
    AND (C.City = E.City
         OR (C.City IS NULL AND E.City IS NULL));