public string WithdrawTransaction(Customer customer) { string accountNo = customer.AccNo; bool isAccNoExist = CheckAccNo(accountNo); if (isAccNoExist) { Customer aCustomer = gateway.GetExistAccount(customer); double balance = aCustomer.Balance; if (customer.Balance <= balance) { var rowAffected = gateway.UpdateWithdraw(customer); if (rowAffected > 0) { return("Withdraw Successfully!"); } else { return("Withdraw Failed!"); } } else { return("Insufficient Balance"); } } else { return("This Account doesn't exist!"); } }