Linq使用小记之Group By

private void cmbStore_SelectedIndexChanged(object sender, EventArgs e)

        {

            DataTable vDt = ParamClass.ChargDt;

            var q = from b in vDt.AsEnumerable() group b by new { storeid = b["STOREID"], charg = b["charg"] } into g select new { g.Key.storeid, g.Key.charg };

            if (q != null && q.Count() > )

            {

                for (int i = ; i < gridPurchaseOrderDetail.Rows.Count; i++)

                {

                    (gridPurchaseOrderDetail.Rows[i].Cells["CHARG"] as DataGridViewComboBoxCell).DataSource = q.ToList();

                    (gridPurchaseOrderDetail.Rows[i].Cells["CHARG"] as DataGridViewComboBoxCell).ValueMember = "charg";

                    (gridPurchaseOrderDetail.Rows[i].Cells["CHARG"] as DataGridViewComboBoxCell).DisplayMember = "charg";

                    (gridPurchaseOrderDetail.Rows[i].Cells["CHARG"] as DataGridViewComboBoxCell).Value = q.ElementAt().charg;

                     getStockNum(i);

                }

            }

        }