/// <summary> /// Get Order Subtotal /// returns the subtotal of all items in a given order. /// </summary> /// <param name="dt"></param> /// <returns></returns> public decimal GetOrderSubTotal(OrderDetailsDS.OrderDetailsDataTable dt) { decimal subtotal = 0.00M; foreach (OrderDetailsDS.OrderDetailsRow dr in dt.Rows) { if (!dr.RowState.Equals(DataRowState.Deleted) || !dr.RowState.Equals(DataRowState.Detached)) { subtotal += (dr.Qty * (decimal)dr.); // not yet complete } } return subtotal; }However, in my case the Price is in the Inventory table and I don't have it in OrderDetails. So, what should be my approach to take here?