如何在Java中使用预处理语句进行select查询？

I had tried several times using prepared statements but it returns SQL exception. here is my code:

我曾多次尝试使用预处理语句，但它返回SQL异常。这是我的代码：

public ArrayList<String> name(String mobile, String password) {
    ArrayList<String> getdata = new ArrayList<String>();
    PreparedStatement stmt = null;
    try {
        String login = "select mobile, password from tbl_1 join tbl_2 on tbl_1.fk_id=2.Pk_ID where mobile=? and password=?";

        String data = "select * from tbl_2  where password='" + password + "'";

        PreparedStatement preparedStatement = conn.prepareStatement(login);

        preparedStatement.setString(1, mobile);
        preparedStatement.setString(1, password);

        ResultSet rs = preparedStatement.executeQuery(login);

        Statement stmts = (Statement) conn.createStatement();

        if (rs.next()) {
            System.out.println("Db inside RS");
            ResultSet data = stmts.executeQuery(data);

            while (data.next()) { /* looping through the resultset */

                getdata.add(data.getString("name"));
                getdata.add(data.getString("place"));
                getdata.add(data.getString("age"));
                getdata.add(data.getString("job"));
            }

        }

    } catch (Exception e) {
        System.out.println(e);
    }

    return getdata;
}

While running this, I got the following SQL exception:

运行此时，我得到以下SQL异常：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '? and password=?' at line 1.

Any suggestion to make this work? any piece of code is appreciated.

有什么建议使这项工作？任何一段代码都表示赞赏。

2 个解决方案

#1

You need to use:

你需要使用：

preparedStatement.executeQuery();

instead of

代替

preparedStatement.executeQuery(login);

when you pass in a string to executeQuery() that query is executed literally and thus the ? is send to the database which then creates the error. By passing query string you are not execution the "cached" prepared statement for which you passed the values.

当你传入一个字符串executeQuery（）时，该字符串执行查询，因此？发送到数据库然后创建错误。通过传递查询字符串，您不会执行为其传递值的“缓存”预准备语句。

#2

For both parameter you use preparedStatement.setString(1, ..); so the first parameter is set two times. but you never set the value for second parameter.

对于这两个参数，您可以使用preparedStatement.setString（1，..）;所以第一个参数设置了两次。但是你永远不会为第二个参数设置值。

so change

所以改变

preparedStatement.setString(1, mobile);
            preparedStatement.setString(1, password);

至

    preparedStatement.setString(1, mobile);
    preparedStatement.setString(2, password);

#1