JDBC-prepareStatement-我应该如何使用它? [英] JDBC - prepareStatement - How should I use it?

问题描述

我在某个地方看到了这个例子:

I saw this example somewhere:

 rs = connection.prepareStatement("select * from table").executeQuery();

如果我要执行类似"从列="hello" "的表中选择*，是否可以使用这种格式?

Could I use this format, if I want to execute a query like this "Select * from table where column = "hello" "?

我通常使用prepareStatement对象的方式如下:

The way in which I usual I use prepareStatement object is something like this:

        String sql = "select * from adresa where column = ?";
        PreparedStatement pre = con.prepareStatement(sql);
        pre.setString(1, i);
        rs = pre.executeQuery();

以后的

我不明白. Pascal Thivent写道，我可以使用带有In参数的简短版本，但是Liu告诉我这是不可能的. :) Anw，使用Pascal的版本，我收到此错误: void不能被取消引用

I don't understand. Pascal Thivent wrote that I can use the short version with In parameters, but Liu tells me this is not possible. :) Anw, using Pascal's version, i receive this error: void cannot be dereferenced

推荐答案

如果查询中没有绑定变量(问号)，则只能使用第一种形式.这只是您发布内容的简化版本.

You can only use the first form if there are no bind variables (question marks) in the query. It's just a shortened version of what you posted.

此外，如果使用简化形式，则将没有机会重用PreparedStatement对象.

Also, if you use the shortened form you won't have the opportunity to reuse the PreparedStatement object.

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