DataTable Linq

DataTable dataTable = pos.Banka();
var groupedData = from b in dataTable.AsEnumerable()
                          group b by b.Field("BANKA_KOD") into g
                          select new
                          {
                              BANKA_KOD = g.Key
                              //ChargeTag = g.Key,
                              //Count = g.Count(),
                              //ChargeSum = g.Sum(x => x.Field("charge"))
                          };

where sorgusu

foreach (var item in groupedData)
        {

            var banka = from b in dataTable.AsEnumerable().Where(x => x.Field("BANKA_KOD") == item.BANKA_KOD)
                        select b;
        }