如何让程序通知我们数据已从数据库中保存，更新或删除 [英] How to make program notify us that data has been save, update or delete from database

问题描述

你好

i想让我的程序在我已经更新或删除数据库中的现有数据时弹出一个消息框，有谁可以告诉我该怎么做？



我尝试过的事情：



这就是我所做的，保存数据



//保存数据

hello
i want to make my program to pop up a messagebox when i already update or remove an existing data in database, can anyone tell me how to do that?

What I have tried:

this is what i have done, for save data

// save data

 openCon();
_com = new MySqlCommand("INSERT INTO `studentdatabase`(`studentID`, `studentName`, `studentIC`, `studentReligion`, `studentForm`, `yearRegistered`) VALUES('" + detailList[0] + "','" + detailList[1] + "','" + detailList[2] + "','" + detailList[3] + "','" + detailList[4] + "','" + detailList[5] + "')", _con);
if (_com.ExecuteNonQuery() == 0) {
                   MessageBox.Show("data not saved");
                }
                else {
                    MessageBox.Show("data saved");
                }

但是我点击了保存按钮后得到了这两条消息

but i got both of the message after i click on the save button

推荐答案

不要这样做！永远不要连接字符串来构建SQL命令。它让您对意外或故意的SQL注入攻击持开放态度，这可能会破坏您的整个数据库。总是使用参数化查询。



连接字符串时会导致问题，因为SQL会收到如下命令：

Don't do it like that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:

SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'

就SQL而言，用户添加的引号会终止字符串，并且您会遇到问题。但情况可能更糟。如果我来并改为输入：x'; DROP TABLE MyTable; - 然后SQL收到一个非常不同的命令：

The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:

SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'

哪个SQL看作三个单独的命令：

Which SQL sees as three separate commands:

SELECT * FROM MyTable WHERE StreetAddress = 'x';

完全有效的SELECT

A perfectly valid SELECT

DROP TABLE MyTable;

完全有效的删除表格通讯和

A perfectly valid "delete the table" command

--'

其他一切都是评论。

所以它确实：选择任何匹配的行，从数据库中删除表，并忽略其他任何内容。



所以总是使用参数化查询！或者准备好经常从备份中恢复数据库。你定期做备份，不是吗？



首先修复整个应用程序，然后继续前进 - 但先修复它！

And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?

Fix that throughout your app first, and then try to move on - but fix that first!

引用：

我想让我的程序在我更新或删除现有数据时弹出一个消息框数据库，谁能告诉我怎么做？

i want to make my program to pop up a messagebox when i already update or remove an existing data in database, can anyone tell me how to do that?

如果你想知道学生是否已经存在于数据库中，请尝试选择学生ID，并查看是否找到了记录。

If you want to know if a student already exist in database, try to SELECT on student id, and see if record was found.

_com = new MySqlCommand("INSERT INTO `studentdatabase`(`studentID`, `studentName`, `studentIC`, `studentReligion`, `studentForm`, `yearRegistered`) VALUES('" + detailList[0] + "','" + detailList[1] + "','" + detailList[2] + "','" + detailList[3] + "','" + detailList[4] + "','" + detailList[5] + "')", _con);

没有必要解决你的问题，但你有另一个问题。

永远不要通过连接字符串来构建SQL查询。迟早，您将使用用户输入来执行此操作，这会打开一个名为SQL注入的漏洞，这对您的数据库很容易并且容易出错。

名称中的单引号你的程序崩溃。如果用户输入像Brian O'Conner这样的名称可能会使您的应用程序崩溃，那么这是一个SQL注入漏洞，崩溃是最少的问题，恶意用户输入，并且它被提升为具有所有凭据的SQL命令。

SQL注入 - 维基百科 [ ^ ]

SQL注入 [ ^ ]

按示例进行SQL注入攻击 [ ^ ]

PHP：SQL注入 - 手册 [ ^ ]

SQL注入预防备忘单 - OWASP [ ^ ]

我该怎么办？解释没有技术术语的SQL注入？ - 信息安全堆栈交换 [ ^ ]

Not necessary a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
SQL Injection Prevention Cheat Sheet - OWASP[^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[^]

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