public static DataSet1 GetDataSet() { DataSet1 dataset = new DataSet1(); var headertransaction = dataset.HeaderTransaction; var detailtransaction = dataset.DetailTransaction; List <HeaderTransaction> header = ReportingHandler.fetchheader(); foreach (HeaderTransaction h in header) { var row = headertransaction.NewRow(); row["TransactionID"] = h.TransactionID; row["TransactionDate"] = h.TransactionDate; row["UserID"] = h.UserID; row["PaymentTypeID"] = h.PaymentTypeID; headertransaction.Rows.Add(row); List <DetailTransaction> detail = ReportingHandler.fetchdetail(h.TransactionID); foreach (DetailTransaction d in detail) { var rowdet = detailtransaction.NewRow(); rowdet["TransactionID"] = d.TransactionID; rowdet["ProductID"] = d.ProductID; rowdet["ProductName"] = d.MsProduct.ProductName; rowdet["ProductPrice"] = d.MsProduct.ProductPrice; rowdet["Quantity"] = d.Quantity; detailtransaction.Rows.Add(rowdet); } } return(dataset); }