Question

请帮帮我：这是一个代码示例。每次按下登录按钮，它都会在空结果集上给出java.sql.SQLExcpetion非法操作

登录按钮的代码：

 private void loginBtnActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:

    con = DatabaseConnection.DBConnect();
    String sql = "SELECT * FROM user_table WHERE user_name = ? AND user_pass = ?";

    try
    {
        getPrivilege(username_Textfield.getText());

        prepStat = con.prepareStatement(sql);
        prepStat.setString(1, username_Textfield.getText());
        prepStat.setString(2,password_Textfield.getText());
        rs = prepStat.executeQuery();

        if(rs.next())
        {
            if (isAdmin == true)
            {
                JOptionPane.showMessageDialog(null,"Login Successful");
                mainDashboard mD = new mainDashboard();
                mD.setVisible(true);
                mD.setPrivilege(isAdmin);
                dispose();


            }else if(isAdmin == false)
            {
                JOptionPane.showMessageDialog(null,"Login Successful");
                userDashboard uD= new userDashboard();
                uD.setVisible(true);
                uD.setPrivilege(isAdmin);
                dispose();
            }

        }else
        {


                JOptionPane.showMessageDialog(null,"The username or password is incorrect","Access Denied", JOptionPane.ERROR_MESSAGE);
                username_Textfield.setBackground(Color.red);
                password_Textfield.setBackground(Color.red);
        }





    }catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, e);
    }


}

连接类的代码：这里的代码是用于数据库连接我有一个名为user的表，它包含user_id，user_name，user_pass，emp_id。所有这些都设置为非空

package guest_house;

//imports needed for the classs

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import javax.swing.JOptionPane;


 /**
 *
 * @author POWER
 */
public class DatabaseConnection {



public static Connection DBConnect()
{
    Connection con = null;
    PreparedStatement preStat = null;
    ResultSet rs = null;

    try
    {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/guest_house?","root","");
        return con;
    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null, e);
        return null;
    }
}



}

Answer 1

您的专栏名称为user_name，user_pass，emp_id，user，并且表格的名称为userName。但是你的sql语句使用userPass，users和"SELECT * FROM user WHERE user_name =? AND user_pass=?"个单词。你必须改变这样的sql语句：

{{1}}

java.sql.SQLException对空结果集

1 个答案: