Linq - Grouping with sum calculation

Question

Linq noob here. How do I correct this?

                var result = (from row in rulestable.AsEnumerable()
                         let sup = row.Field

        

Answer 1

When I run this query I failed in visual studio. On More search found the following and worked well in my system.

var result = (from row in rulestable.AsEnumerable() 
             group row by new {sup= row.Field("Supplier"), 
                              vat=row.Field("VatRate")} into grp = Group 
             select new With 
             {.Supplier = sup, 
              .Amount = grp.Sum(r => r.Field("Amount")),
              .Advance  = grp.Sum(r => r.Field("Advance")),
              .Balance  = grp.Sum(r => r.Field("Balance")),
              .VatRate  = vat
              }
             ).ToList();