Question

It will be hard to explain but I’ll try
I’ve got a table with some fields, and that table got subtable with rows (I’m not talking about SQL, its DB4O, but I use linq). Rows got timefrom and timeto, example:

maintable:
Description,
CreateDate,
....
mainTableRows:
08:00,
09:00,
some description

Now I need to make a query that will sum hours from rows, like this:

09:00-08:00 = 1hour(first row) + 10:00-09:00 (second row)

and so on.

Something like:

var item = from mainTable m 
           select new
             { 
               m.Id, 
               Hours = m.Rows.Sum(c=> new { Hour = c.TimeTo - c.TimeFrom }) 
             }

Thanks all for help, this is mine full solution:

var item = from mainTable m 
               select new
                 { 
                   m.Id, 
                   Hours = String.Format("{0:HH:mm}", (new DateTime((p.TimesheetRows.Aggregate(TimeSpan.Zero, (subtotal, t) => subtotal += (t.TimeTo - t.TimeFrom)).Ticks))))
                 }

Answer 1

If you want the total elapsed time, you can do:

 var item = from mainTable m 
       select new
         { 
           m.Id, 
           Hours = m.Rows
                    .Select(c => c.TimeTo - c.TimeFrom)
                    .Aggregate( (working, next) => working.Add(next) )
                    .TotalHours
         }