Question

I have a untyped DataTable that looks like this (srcTbl):

date            col_1   col_2 ...  col_n
1.3.2010 00:00  12.5    0     ...  100 
1.3.2010 01:00  0       0     ...  100 
1.3.2010 22:00  0       0     ...  100 
1.3.2010 23:00  12.5    0     ...  100 
...
31.3.2010 00:00 2       0     ...  100
31.3.2010 01:00 2       0     ...  200

I need to sum up the rows grouped by dates to get a DataTable like that (dstTbl):

date,           col_1   col_2 ...  col_n
1.3.2010        15      0     ...  400
...
31.3.2010       4       0     ...  300

Is this possible by using LINQ and if then how?

Answer 1

Okay, So you can achieve it like this. This is a working version so you shouldn’t have much problem.

DataTable myDataTable = new DataTable();
myDataTable.Columns.Add("Date", typeof(DateTime));
myDataTable.Columns.Add("Col1", typeof(int));
myDataTable.Columns.Add("Col2", typeof(int));
myDataTable.Columns.Add("Col3", typeof(int));

        var datarow1 = myDataTable.NewRow();
        datarow1.SetField("Date", DateTime.Parse("01/03/09 00:01:00"));
        datarow1.SetField("Col1", 12);
        datarow1.SetField("Col2", 0);
        datarow1.SetField("Col3", 100);

        var datarow2 = myDataTable.NewRow();
        datarow2.SetField("Date", DateTime.Parse("01/03/09 01:03:00"));
        datarow2.SetField("Col1", 12);
        datarow2.SetField("Col2", 0);
        datarow2.SetField("Col3", 100);

        var datarow3 = myDataTable.NewRow();
        datarow3.SetField("Date", DateTime.Parse("01/03/09 02:05:00"));
        datarow3.SetField("Col1", 0);
        datarow3.SetField("Col2", 0);
        datarow3.SetField("Col3", 100);

        var datarow4 = myDataTable.NewRow();
        datarow4.SetField("Date", DateTime.Parse("10/10/09 00:03:00"));
        datarow4.SetField("Col1", 2);
        datarow4.SetField("Col2", 0);
        datarow4.SetField("Col3", 100);

        var datarow5 = myDataTable.NewRow();
        datarow5.SetField("Date", DateTime.Parse("31/03/09 01:03:00"));
        datarow5.SetField("Col1", 2);
        datarow5.SetField("Col2", 0);
        datarow5.SetField("Col3", 100);

        var datarow6 = myDataTable.NewRow();
        datarow6.SetField("Date", DateTime.Parse("31/03/09 03:04:00"));
        datarow6.SetField("Col1", 2);
        datarow6.SetField("Col2", 0);
        datarow6.SetField("Col3", 100);

        myDataTable.Rows.Add(datarow1);
        myDataTable.Rows.Add(datarow2);
        myDataTable.Rows.Add(datarow3);
        myDataTable.Rows.Add(datarow4);
        myDataTable.Rows.Add(datarow5);
        myDataTable.Rows.Add(datarow6);

        var q = (from t in myDataTable.AsEnumerable()
                 group t by new {t.Field<DateTime>("Date").Day, t.Field<DateTime>("Date").Month, t.Field<DateTime>("Date").Year}
                 into temp
                    select myDataTable.LoadDataRow(
                    new object[]
                        {
                            string.Format("{0}.{1}.{2}", temp.Key.Day, temp.Key.Month, temp.Key.Year),
                            temp.Sum(r => r.Field<int>("Col1")),
                            temp.Sum(r => r.Field<int>("Col2")),
                            temp.Sum(r => r.Field<int>("Col3")),
                        }, LoadOption.PreserveChanges));

        DataTable newTable = q.CopyToDataTable();