CodeGo.net>如何获得最大日期与加入记录？

select  MAX(d.DepartureDateRange),MAX(d.ReturnDateRange)   
from Tour t join
TourCategory tc on t.ID = tc.TourID
join TourDates td on t.ID = td.TourID
join Dates d on d.ID = td.DatesID
where tc.CategoryID = 3 and t.ID = 12 

数据库图在这里->

例如,join就是这样,但我无法获得Max of DepartureDateRange& ReturnDateRange

var query2 = from t in db.Tour
    join tc in db.TourCategory on t.ID equals tc.TourID
    join td in db.TourDates on t.ID equals td.TourID
    join d in db.Dates on td.DatesID equals d.ID
    where tc.CategoryID == 3
    select new IndexTour
    {
        ID = t.ID,
        TourName = t.TourName,
        //DepartureDateRange = 
        //ReturnDateRange = 
        Description = t.SmallDesc,
        Price = t.Price,
        CoverPhotoUrl = t.CoverPhotoUrl,
        TourProgram = t.TourDesc
    };

提前致谢.

var query2 = 
    from t in db.Tour
    join tc in db.TourCategory on t.ID equals tc.TourID
    where tc.CategoryID == 3
    // join dates aggregates grouped by tour id
    join tdates in
        from td in db.TourDates 
        join d in db.Dates on td.DatesID equals d.ID
        group d by td.TourID into grp
        select new 
        { 
            tourID = grp.Key, 
            departure = grp.Max(g => g.DepartureDateRange), 
            rtrn = grp.Max(g => g.ReturnDateRange)
        }
    on t.ID equals tdates.tourID
    select new IndexTour
    {
        ID = t.ID,
        TourName = t.TourName,
        DepartureDateRange = tdates.departure,
        ReturnDateRange = tdates.rtrn,
        Description = t.SmallDesc,
        Price = t.Price,
        CoverPhotoUrl = t.CoverPhotoUrl,
        TourProgram = t.TourDesc
    };