text: WITH CTE_HighestPeakNameAndElevationByCountry (Country, [Highest Peak Name], [Highest Peak Elevation], Mountain) 
  AS (SELECT 
         c.CountryName AS Country,
  	   ISNULL(p.PeakName, '(no highest peak)') AS [Highest Peak Name],
         ISNULL(MAX(p.Elevation), 0) AS [Highest Peak Elevation],
  	   ISNULL(m.MountainRange, '(no mountain)') AS Mountain
    FROM Countries AS c
  LEFT OUTER JOIN MountainsCountries AS mc
      ON mc.CountryCode = c.CountryCode
  LEFT OUTER JOIN Mountains AS m
      ON m.Id = mc.MountainId
  LEFT OUTER JOIN Peaks AS p
      ON p.MountainId = mc.MountainId
   GROUP BY c.CountryName, m.MountainRange, p.PeakName)
  
  SELECT TOP (5) * 
    FROM CTE_HighestPeakNameAndElevationByCountry
   ORDER BY Country, [Highest Peak Name]