Bernerd

你可以用 max 在…上 NumOfRentDays 然后 group 整个结果由 carid .

应该是这样的:

SELECT CarId, Make, Model, max(NumOfRentDays) AS TotalRentDays FROM Cars
JOIN Rents ON Cars.CarId= Rents.Cars_CarId  GROUP BY CarId ORDER BY TotalRentDays DESC;