如何在sql server中显示主键的最大日期

Question

with bookingdetails as (
    select  booking_master.booking_datetime as newdatetime, 
            booking_master.ETA as neweta 
    from booking_master where booking_ID='143'
)

上面的输出是：

newdatetime             neweta
2016-10-02 03:00:00.000 2016-10-05 03:00:00.000

比我运行：

with comparetrucklog as (
    select  truck_log.truck_id as bookedtruck, 
            truck_log.ETA as eta 
    from truck_log 
    where (select newdatetime from bookingdetails) between truck_log.pickupdate and truck_log.ETA 
        or (select neweta from bookingdetails) between truck_log.pickupdate and truck_log.ETA
)

在预订时，comparetrucklog的结果列37重复了两次，但我需要在eta中仅显示最大日期时间。

我怎样才能做到这一点？

Answer 1

为什么简单的max（）会正常工作？

 select bookedtruck, max(eta) from bookingmaster group by bookedtruck