public void actionPerformed(ActionEvent e)
	{
		if(e.getSource()==Enter)
		{
			String username , password;
			username = name.getText();
		    password = pwd.getText();
			try
			{
				Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
			}
			catch (ClassNotFoundException ce)
			{
				JOptionPane.showMessageDialog(ss,ce.getMessage());
			}
			if(stu.isSelected())
			{
				try
			    {
					Connection con = DriverManager.getConnection("jdbc:odbc:sysdb","sa","");
				    Statement stmt = con.createStatement();
				    ResultSet rs = stmt.executeQuery("select * from STU");
				    while(rs.next())
				    {
						if((rs.getString("ID").equals(username))&&(rs.getString("Pwd").equals(password)))
					    {        
							JOptionPane.showMessageDialog(ss,"½ɹ");
							Students stu = new Students();
					    }
					    else
					    {
						    JOptionPane.showMessageDialog(ss,"¼ʧ");
					    }
				    }
				    rs.close();
				    stmt.close();
			    }
			    catch (SQLException se)
			    {
				    JOptionPane.showMessageDialog(ss,se.getMessage());
			    }
			}
			else if(tch.isSelected())
			{
				try
				{
					Connection con = DriverManager.getConnection("jdbc:odbc:systchdb","sa","");
					Statement stmt = con.createStatement();
					ResultSet rs = stmt.executeQuery("select * from TCH");
					while(rs.next())
					{
						if((rs.getString("ID").equals(username))&&(rs.getString("Pwd").equals(password)))
						{
							JOptionPane.showMessageDialog(ss,"½ɹ");
						}
						else
						{
							JOptionPane.showMessageDialog(ss,"¼ʧ");
						}
					}
				}
				catch (SQLException se)
				{
					JOptionPane.showMessageDialog(ss,se.getMessage());
				}
			}
		}
		else
		{
			System.exit(0);
		}
	}