Multiple Group data

Question

I have a set of data as below from my Payment table

DateIssue             | Amount | CoursePaidForMonth | 
  2/3/2011 9:54:07 PM | 2000.00|          2
 2/27/2011 2:22:58 PM |   80.00|          2
 3/5/2011 11:14:56 PM |   80.00|          3
 3/27/2011 2:22:58 PM |   80.00|          2
 2/8/2011 6:32:45 PM  |   80.00|          2

I would like to perform two sets of grouping for the data above:

1. The closing date is on the 27 of every month, so I would like to group all the data from 27 till 26 of next month into a group. This is done successfully from the gName. NO PROBLEM !! Check out the output as the image below.

   DateIssue             AppendCommToMonthΞΞ CoursePaidForMonthΞΞ TotalAmountΞΞ 
   2/8/2011 6:32:45 PM            2                    2             2080.00
   2/27/2011 2:22:58 PM           3                    2              160.00
   3/27/2011 2:22:58 PM           4                    2               80.00
   

2. Now I would like to perform another grouping on the same query. I would like to group the CoursePaidForMonth as well. Meaning to say, the final output should show 4 lines of records instead of just 3, it group by from 27 this month till 26 of next month into a group and also by CoursePaidForMonth. How to do this?

   DateIssue             AppendCommToMonthΞΞ CoursePaidForMonthΞΞ TotalAmountΞΞ 
   2/8/2011 6:32:45 PM            2                    2             2080.00
   2/27/2011 2:22:58 PM           3                    2              80.00
   3/5/2011 11:14:56 PM           3                    3              80.00
   3/27/2011 2:22:58 PM           4                    2              80.00
   

My code is here:

var result = from p in db.Payments
               join soi in db.SaleOrderItems on p.ReferenceId equals soi.Id
               join ct in db.CourseByTutors on soi.InventoryOrCourseId equals ct.CourseId                              
               where p.PayType == (int)PayTypes.PayCourseFee
               && ct.TutorId == tutorId
               let gName = (p.DateIssue.Value.Day < 27) ? (p.DateIssue.Value.Month) : (p.DateIssue.Value.Month % 12 + 1)
               group p by new { gName} into g
               select new
               {
                  DateIssue = g.Select(x => x.DateIssue).First(),
                  AppendCommForWhichMonth = g.Key.gName,
                  CoursePaidForMonth = g.Select(x => x.CoursePaidForMonth).First(),
                                 TotalAmount = g.Sum(x => x.Amount),
               };

Please advice..

Answer 1

You need to include the CoursePaidForMonth into your key. Something like this:

var query = from p in db.Payments
            join soi in db.SaleOrderItems
                on p.ReferenceId equals soi.Id
            join cbt in db.CourseByTutors
                on soi.InventoryOrCourseId equals cbt.CourseId
            where p.PayType == (int)PayTypes.PayCourseFee && cbt.TutorId == tutorId
            orderby p.DateIssue
            let AppendCommForWhichMonth = p.DateIssue.Month + p.DateIssue.Day < 27 ? 0 : 1
            group p
                by new { AppendCommForWhichMonth, p.CoursePaidForMonth }
                into g
            select new
            {
                g.First().DateIssue,
                g.Key.AppendCommForWhichMonth,
                g.Key.CoursePaidForMonth,
                TotalAmount = g.Sum(p => p.Amount),
            };