请问这是什么问题？

我运行的代码是这样的：<%@ page contentType="text/html; charset=gb2312" language="java" %>
<%@ page import="java.sql.*" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
</head>
<font color="#00FF00" size="+3" face="方正舒体">您可以选报的课程为 </font></p>
<p>&nbsp; </p>
<form action="checkGrourp.jsp" method="post">
<table border="1" align="center">
    <tr><td width="54">课程号</td>
        <td width="54">课程名</td>
        <td width="57">预修课</td>
        <td width="58">系别</td>
        <td width="59">班级号</td>
        <td width="69">教室号</td>
<td width="88">上课时间</td>
        <td width="83">选择</td></tr>
<%
String cour_id,name,dep,prepare,class_id,room_id,cour_time;
String stu_id="S0001001";
Statement sql=null;
Connection con=null;
try{
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
}
catch(ClassNotFoundException e){
out.print(e);
}
try{
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/student","root","");
String condition="select DISTINCT course.id,course.name,course.prepare,course.dep , "+
"classes.id as class_id,classes.room_id,classes.cour_time "+
"from course,classes "+
"where classes.cour_id=course.id and "+
  "classes.id in "+
"( select classes.id from classes,student,course  "+
"where classes.id not in( select class_id from enrol where stu_id='"+stu_id+"') "+
"and ( student.department=course.dep or course.dep ='public')  "+
"and course.id=classes.cour_id and student.id='"+stu_id+"') ";ResultSet rs = sql.executeQuery(condition);while(rs.next()){
cour_id=rs.getString("course.id");
name=rs.getString("course.name");
dep=rs.getString("course.prepare");
prepare=rs.getString("course.dep");
class_id=rs.getString("classes.id");
room_id=rs.getString("room_id");
cour_time=rs.getString("cour_time");
%>
<tr><td><%=cour_id%></td>
    <td><%=name%></td>
    <td><%=dep%></td>
    <td><%=prepare%></td>
    <td><%=class_id%></td>
    <td><%=room_id%></td>
    <td><%=cour_time%></td>
    <td> <input type="checkbox" name="chkbx" value="<%=cour_id%>")></td></tr>
<%}
}catch(SQLException e){
out.print(e);
}%>
</table>
<p>&nbsp;</p>
<p align="center"> 
    <input name="确定" type="submit" id="确定" value="确定">
</p>
</form>
</body>
</html>