更改表外键从 java 到 mysql

发布于 2024-12-18 21:01:17 字数 463 浏览 3 评论 0原文

好吧，我想对我的数据库进行修改，所以我需要使用 alter table，但 java 似乎在做这件事时遇到了问题。

这句话

ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id);

你怎么执行呢？

我正在这样做：

rawStatement="ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id);";
currentStatement = conn.createStatement();
currentStatement.execute(rawStatement);

最后一行正确吗？

据我所知，execute 必须运行所有内容。

原文

Well, I want to make a modification in my database, so I need to use alter table but java seems to have problems making that.

This is the sentence

ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id);

how do you execute it?

I was doing this:

rawStatement="ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id);";
currentStatement = conn.createStatement();
currentStatement.execute(rawStatement);

is the last line correct?

As far I know, execute must run everything.

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时间海 2024-12-25 21:01:17

使用这个< /a>：

executeUpdate()

而不是

execute()

Also if the Constraint is已经存在，它将抛出异常

您应该注意的其他事项：

用户是否有权更改表？

Use this:

executeUpdate()

instead of

execute()

Also if the constraint is already present it will throw an exception

Other things you should look out for:

Does the user have the privileges to alter the table?

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残花月 2024-12-25 21:01:17

尝试使用下面的代码：

rawStatement="ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id)"; 
PreparedStatement ps = conn.prepareStatement(rawStatement);
ps.executeUpdate();

Try with the below code:

rawStatement="ALTER TABLE loans ADD FOREIGN KEY (id_reader) REFERENCES readers (id)"; 
PreparedStatement ps = conn.prepareStatement(rawStatement);
ps.executeUpdate();

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