JDBC错误：在开始结果集之前 [英] JDBC Error: Before start of result set

问题描述

我在Java eclipse中有一条错误消息。我在MySql中有一个数据库，它有colomns String user_name，int id_time，int id_desk，int user_password。我希望使用

I have an error message in Java eclipse. I have a database in MySql and it has colomns String user_name, int id_time, int id_desk, int user_password. I want to one row's columns data with using

一行的列数据public ArrayList showReservation（String user_name）抛出SQLException {

public ArrayList showReservation(String user_name) throws SQLException{

    // array list keeps the information
    ArrayList<String> showReservation = new ArrayList<String>();
    try{

        String getReservationSql = "SELECT * FROM reservation " 
                +"WHERE user_name ='" + user_name + "';";
        rs = stmt.executeQuery(getReservationSql);

        // first element of the array list keeps user name
        showReservation.add("" + rs.getString("user_name")); 

        // second element of the array list keeps id of the desk which is selected by user
        showReservation.add("" + rs.getInt("id_time")); 

        // third element of the array list keeps id of the time interval which is selected by user
        showReservation.add("" + rs.getInt("id_desk"));  

        // forth element of the array list keeps user's password which is generated automatically in a controller class
        showReservation.add("" + rs.getInt("user_password")); 

    }catch (SQLException ex) {
        System.out.println("Error: " + ex.getMessage());
    }
    return showReservation;
}

但是当我运行此代码时出现错误：在开始结果集之前。
如何修复此错误？
谢谢

but when i run this code i get an error: Before start of result set. how can i fix this error? thanks

推荐答案

使用 next $ c> ResultSet getter方法

Use next before attempting to call any of the ResultSet getter methods

rs = stmt.executeQuery(getReservationSql);
if (rs.next()) {
   ...
}

除此之外：考虑使用准备好的陈述

这篇关于JDBC错误：在开始结果集之前的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！