Question

I have existing code that works very well and it finds the maximum value of a data column in the data table. Now I would like to refine this and find the maximum value per empid.
What change would be needed? I do not want to use LINQ.

I am right now using this: memberSelectedTiers.Select(“Insert_Date = MAX(Insert_Date)”)
and I need to group it by Empid.

My code is as below.

        DataTable memberApprovedTiers = GetSupplierAssignedTiersAsTable(this.Customer_ID, this.Contract_ID);

        //get row with maximum Insert_Date in memberSelectedTiers
        DataRow msRow = null;
        if (memberSelectedTiers != null && memberSelectedTiers.Rows != null && memberSelectedTiers.Rows.Count > 0)
        {
           DataRow[]  msRows = memberSelectedTiers.Select("Insert_Date = MAX(Insert_Date)");
           if (msRows != null && msRows.Length > 0)
           {
               msRow = msRows[0];
           }
        }

Answer 1

You can use LINQ to achieve this. I think the following will work (don’t have VS to test):

var grouped = memberSelectedTiers.AsEnumerable()
                                 .GroupBy(r => r.Field<int>("EmpId"))
                                 .Select(grp => 
                                     new { 
                                         EmpId = grp.Key
                                       , MaxDate = grp.Max(e => e.Field<DateTime>("Insert_Date"))
                                     });