SELECT TOP 1 COUNT(CategoryID) KAT_SAY,CUS.Name,CUS.LastName,CUS.BirthDate FROM Sales SLS LEFT JOIN Products PRO ON SLS.ProductID=PRO.ProductID
LEFT JOIN Customers CUS ON SLS.CustomerID=CUS.CustomerID
GROUP BY SLS.CustomerID,CUS.Name,CUS.LastName,CUS.BirthDate
ORDER BY KAT_SAY,BirthDate DESC