该代码，急用

try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String url2 = "jdbc:odbc:stu";
Connection conn2 = DriverManager.getConnection(url2);
Statement stat2 = conn2.createStatement();
String sql2 = "select * from student where xuehao='"+xuehaojComboBox.getSelectedItem().toString()+"';";
ResultSet rSet2 = stat2.executeQuery(sql2);
xuehaojComboBox.removeAllItems();
xuehaojComboBox.addItem(" ");
while(rSet2.next()){
xuehaojComboBox.addItem(rSet2.getString(1));
}
conn2.close();
} catch(java.lang.Exception exec) {
jbjg.setText("加入班级编号错误!");
}

以上代码竟出现加入编辑错误，怎么改？初学者不会，谢谢啦！