ResultSet不适用于INSERT查询？错误消息：类型不匹配：无法从int转换为String [英] ResultSet is not for INSERT query? Error message: Type mismatch: cannot convert from int to String

问题描述

我认为我在'结果集'中弄错了。我插入数据的代码是：

I think I got it wrong at the 'resultset'. My code for inserting data is :

ResultSet columns = statement.executeUpdate("INSERT INTO Feedback (Username, Feedbacks) VALUES( '" + user + "','"+ msg +"')");

编译错误是：

类型不匹配：无法从int转换为String

Type mismatch: cannot convert from int to String

你能帮助我吗？

推荐答案

语句#cuteUpdate（） 不返回 ResultSet ，但是 int 表示受影响的行。修复如下。

Statement#executeUpdate() doesn't return a ResultSet, but an int representing the affected rows. Fix it as follows.

int affectedRows = statement.executeUpdate(sql);

或者，如果您对受影响的行数不感兴趣，请忽略它。

Or if you aren't interested in the amount of affected rows, just ignore it.

statement.executeUpdate(sql);

顺便说一句，编译错误本身就很奇怪。你不是在看错线吗？该错误告诉您正在尝试将 int 结果分配给 String ，但您的代码显示您'重新尝试将 int 结果分配给 ResultSet 。

By the way, the compilation error at its own is weird. Aren't you looking at the wrong line? The error tells that you're trying to assign an int result to a String, but your code shows that you're trying to assign int result to a ResultSet.

如果用户和 msg 是用户控制输入的一部分，那么这段代码很容易 SQL注入 攻击。我强烈建议用 Statement rel =nofollow> PreparedStatement 然后。另请参见本教程如何使用预准备语句。

That said and unrelated to your current problem, if user and msg are parts of user-controlled input, then this piece of code is prone to SQL injection attacks. I strongly recommend to replace Statement by PreparedStatement then. See also this tutorial how to use prepared statement.

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