错误:参数索引超出范围(2>参数数量，即1) [英] ERROR : Parameter index out of range (2 > number of parameters, which is 1)

问题描述

我在这里搜索找到错误的解决方案，但没有一个匹配我的问题，所以有人可以帮助我在我的代码中找到错误吗??

i searched here to find solution for my error but no one match my problem , So is there anyone help me to find the error in my code !?

 textField_1.addActionListener(new ActionListener() {
                            public void actionPerformed(ActionEvent e) {

            try{
            Object selected = list_1.getSelectedValue();
                Connection conn = null;
                conn=DriverManager.getConnection("jdbc:mysql://localhost/flyer","root","000");
                Statement st= conn.createStatement();

                String query = "INSERT INTO flyer_item (discount) SELECT price*? FROM `item` where item_name='?' ";

                // PreparedStatement ps = null;

                int i = Integer.valueOf((textField_1.getText()));
                i=i/100;
                java.sql.PreparedStatement ps = conn.prepareStatement(query);
                ps.setInt(1,i);
                ps.setString(2, selected.toString());
                ps.executeUpdate();
                st.executeUpdate(query);



            } catch (SQLException se){
                System.out.println(se.getMessage());

            }

                            } } );

注意:mysql声明它已在workbench中成功运行.谢谢

Note : mysql statement it's running successfully in workbench . thank you

推荐答案

删除问号占位符周围的单引号

Remove the single quotes around the question mark placeholder

更改此:

  where item_name='?'

对此:

  where item_name= ?

那应该可以解决问题.

使用单引号，prepareStatement将单引号视为包含字符串文字.字符串文字碰巧包含一个问号，但它没有将那个问号视为绑定占位符.

With the single quotes, the prepareStatement is seeing the single quotes as enclosing a string literal. The string literal happens to contain a question mark, but it's not seeing that question mark as a bind placeholder.

因此，生成的准备好的语句只有一个占位符.这就是 setString 调用遇到错误的原因:没有第二个占位符可为其提供值.

So the resulting prepared statement only has a single placeholder. Which is why the setString call is encountering an error: there is no second placeholder to supply a value for.

-

编辑

也从代码中删除此行:

            st.executeUpdate(query);

并删除此行:

            Statement st= conn.createStatement();

(代码正在创建并使用准备好的语句 ps .)

(The code is creating and using a prepared statement ps.)

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