DataClasses1DataContext myContext = new DataClasses1DataContext();var transactionsUngrouped =from transactions in myContext.Transactionswhere transactions.transactionGrouped == falseselect transactions;foreach (Transaction transaction in transactionsUngrouped){if (transaction.transactionContraAccountName.Contains("something")){// Change group and submut changestransaction.transactiongroupID = 1;myContext.SubmitChanges();// Update 'personal_financeDataSet.Transactions' table.this.transactionsTableAdapter.Fill(this.personal_productsDataSet.Transactions);}}