我是Riya a B.Tech。学生和我必须就大学管理系统这个主题制作一个corejava项目。我使用MS Access创建了所需的数据库。我在这里附带的代码中遇到问题。实际上我想更新数据库中的数据,所以我在其中一个中制作了2个帧。在输入时询问第二帧是否打开并要求更新输入标记...当我输入要更新的标记时,会打开一个对话框,显示“标记已成功更新”。直到这里我没有任何问题..问题是当我打开数据库时,我看到实际上Marks没有更新那里。所以请有人帮我解决这个问题。
代码如下:
1ST FRAME
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
class MyFrame03 extends JFrame implements ActionListener {
JLabel l1;
JTextField t1;
JPanel p1, p2;
JButton b1;
Connection con;
PreparedStatement pst;
String s1;
MyFrame03() {
setLayout(new GridLayout(4, 1));
setTitle("Enter Data Required");
setBackground(Color.blue);
l1 = new JLabel("Roll no");
t1 = new JTextField(12);
p1 = new JPanel();
p2 = new JPanel();
b1 = new JButton("SUBMIT");
p1.add(l1);
p1.add(t1);
p2.add(b1);
add(p1, "Center");
add(p2, "South");
b1.addActionListener(this);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400, 500);
setVisible(true);
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
if (con != null)
System.out.println("Connection Established");
}
catch (Exception e) {
System.out.println("exception");
}
}
public void actionPerformed(ActionEvent e1) {
if (e1.getSource() == b1) {
s1 = t1.getText();
try {
pst = con.prepareStatement("insert into stud values(?)");
pst.setString(1, s1);
pst.executeUpdate();
con.commit();
con.close();
}
catch (SQLException e) {
System.out.println("except1");
}
MyFrame04 m1 = new MyFrame04(s1);
dispose();
}
}
public static void main(String s[]) throws SQLException {
MyFrame03 m1 = new MyFrame03();
}
}
第二次FRAME
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
class MyFrame04 extends JFrame implements ActionListener {
JLabel l1;
JTextField t1;
JPanel p1, p2;
JButton b1;
String s1, s2;
Connection con;
PreparedStatement pst;
public MyFrame04(String s1) {
this.s1 = s1;
setLayout(new GridLayout(4, 1));
setTitle("Update Marks");
setBackground(Color.blue);
l1 = new JLabel("Enter Marks");
t1 = new JTextField(12);
b1 = new JButton("SUBMIT");
p1 = new JPanel();
p2 = new JPanel();
p1.add(l1);
p1.add(t1);
p2.add(b1);
add(p1, "Center");
add(p2, "South");
b1.addActionListener(this);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400, 500);
setVisible(true);
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
if (con != null)
System.out.println("Connection Established");
}
catch (Exception e) {
System.out.println("exception");
}
}
public void actionPerformed(ActionEvent e1) {
if (e1.getSource() == b1) {
s2 = t1.getText();
try {
pst = con.prepareStatement("UPDATE stud set Marks=? WHERE Roll no=?");
pst.setString(1, s2);
pst.setString(2, s1);
pst.executeUpdate();
con.commit();
con.close();
}
catch (SQLException e) {
System.out.println("except1");
}
JOptionPane.showMessageDialog(this, "Marks updated succesfully");
dispose();
}
}
}
三江源
答案 0 :(得分:2)
没有Swing,您的数据库访问代码是否有效?最简单的方法是:
class HelloDatabase {
public static void main(String[] args) {
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
if (con != null) {
int marks = 1, roll = 1; // or whatever (your data here)
System.out.println("Connection Established");
PreparedStatement pst = con.prepareStatement("UPDATE stud SET marks=? WHERE roll_num=?");
pst.setString(1, marks);
pst.setString(2, roll);
pst.executeUpdate();
con.commit();
con.close();
}
}
catch (Exception e) {
System.out.println("exception");
}
}
}
如果这得到一个句柄并正确访问您的数据库,那么你很幸运。
顺便说一下 - 这可能实际上是你的问题 - 我注意到你原来帖子中的SQL查询含糊不清:
UPDATE stud set Marks=? WHERE Roll no=?
根据我的理解,