Question

I want to order the selected values by ascending distinct date.

For example i have these values in my database.

ID | Value | Date 
 1 | 35    | 2012/01/20
 2 | 0     | 2012/01/20
 3 | 10    | 2012/02/01
 4 | 0     | 2012/02/01
 5 | 0     | 2012/03/01
 6 | 0     | 2012/03/01

Since ID 1 has a value on the 20th of January and ID 3 has a value on the 1st of February i want these two dates to be selected to my list of distinct date values. But for ID 5 and 6 both have value 0. So if value is 0 i also want the value 0 to be added.

Now my linqquery looks like this

        var totalHours = (from u in context.Users
                          join r in context.Reports on u.Id equals r.UserId
                          join w in context.Weeks on r.Id equals w.ReportId
                          join d in context.Days on w.DayId equals d.Id
                          orderby d.Date ascending
                          where r.weekNr.Equals(currentWeek)
                          select d.Hour).ToList();

But this query of course gives me 35,0,10,0,0,0 as result.
Though I want it to give me 35,10,0

I dont want do pick out distinct values, say if February 1st and February 2nd has the same values. I want both these values to be added.

Answer 1

I would suggest to first select what you need from the first query:

 var totalHours = (from u in context.Users
                          join r in context.Reports on u.Id equals r.UserId
                          join w in context.Weeks on r.Id equals w.ReportId
                          join d in context.Days on w.DayId equals d.Id
                          orderby d.Date ascending
                          where r.weekNr.Equals(currentWeek)
                          select new {id = r.UserId, hour = d.Hour, date = d.Date}).ToList();

In the above I assumed that d.Hour corresponds to the Value field in your example.

Then group by date, order by hour descending and select the first item from each group:

var distinctValues = totalHours
                .GroupBy(th => th.Date)
                .OrderByDescending(v => v.Max(o => o.Hour))
                .Select(g => g.First());

UPDATE

To return just the list of integers for the Hour property use this instead of the above statement:

 var distinctValues = totalHours
                .GroupBy(th => th.Date)
                .OrderByDescending(v => v.Max(o => o.Hour))
                .Select(g => g.First().Hour)
                .ToList();

UPDATE 2

Can you try this ?

var distinctValues = totalHours
                .GroupBy(th => th.Date)
                .Select(g => g.OrderByDescending(e => e.Hour))
                .Select(g => g.First().Hour)
                .ToList();