请各路英雄好汉解决读取数据库值的两级关联下拉菜单问题

Question

关联就是了，一个变化触发另一个变化好像javascript 可以 实现！

Answer 1

完全可以用JAVASCRIPT来实现，当然你的JAVASCRIPT里面的数组要使用JAVA程序来生成。

Answer 2

<%
DBConnect dbc=null;
ResultSet rs=null;
String sql=null;
String college=request.getParameter("college");
if(college!=null) college=college.trim();
String classname=request.getParameter("class_name");
String order=request.getParameter("order");
if(order==null)
order="stucode";
%>
<script language="javascript">
function jump(obj)
{
var url="class.jsp?college="+obj.options[obj.selectedIndex].value;
location.href=url;
}function jump2(obj)
{
var url="class.jsp?college="+form1.college.options[form1.college.options.selectedIndex].value+"&class_name="+obj.value;
location.href=url;
}
</script>
<%try
{
dbc=new DBConnect("user");%>
<form name="form1" action="post">
<%
if(sign!=2)
{
%>
<select name="college" onChange="jump(this)"><%
if(sign==0)
sql="select * from college";
else if(sign==1)
sql="select * from college where col_code='"+sign_s+"'";
rs=dbc.executeQuery(sql);
while(rs.next())
{
String code=rs.getString("col_code");
if(code!=null) code=code.trim();
String name=rs.getString("col_name").trim();
if(code!=null&&college==null) college=code;
if(code.equals(college))
out.println("<option selected value=\""+code+"\">"+name+"</option>");
else
out.println("<option  value=\""+code+"\">"+name+"</option>");}
%></select>
<select name="classname" onChange="jump2(this)">
<option value="" >选择班级</option>
<%if(sign==0||sign==1)
sql="select * from class where col_code='"+college+"'";
if(college!=null) 
{
rs=dbc.executeQuery(sql);
while(rs.next())
{
String class_code=rs.getString("ca_code").trim();
String class_name=rs.getString("ca_name").trim();
if(classname!=null&&classname.equals(class_code))
out.println("<option selected value=\""+class_code+"\">"+class_name+"</option>");
else
out.println("<option value=\""+class_code+"\">"+class_name+"</option>");
}
}
%>
</select>
<%
}
%>
</form>
</td>
</tr>
<tr>
 <td  height=30 colspan=11 valign="middle" bgcolor=#EFEFEF>
 <div align="center">
 <%
  if(classname!=null&&(sign==0||sign==1))
{
sql="select * from student WHERE SUBSTRING(xuehao, 1, 5) = '"+classname+"'";
}
else 
{
sql="select * from student WHERE SUBSTRING(xuehao, 1, 5) = '"+sign_s+"'";
classname=sign_s;
}
if(classname!=null)
{%>
<tr height="35" > 
<td width="5%" height=35><div align="center">学号</div></td>
<td width="5%" height=35><div align="center">姓名</div></td>
<td width="2%"><div align="center">性别</div></td>
<td width="8%"><div align="center">出生日期</div></td>
<td width="10%"><div align="center">身份证</div></td>
<td width="8%"><div align="center">省份</div></td>  
     </tr>
<%
rs=dbc.executeQuery(sql);
while(rs.next())
{
String xuehao=rs.getString("xuehao");
String name=rs.getString("name");
String sex=rs.getString("sex");
String birthday=rs.getString("birthday");
String id_card=rs.getString("id_card");
String province=rs.getString("province");
if(name==null)
name="";
if(sex==null)
sex="没填写";
if(birthday==null)
birthday="没填写";
if(id_card==null)
id_card="没填写";
if(province==null)
province="没填写";
%>
<tr >
<td width="5%" height=35><div align="center">&nbsp;<%= xuehao %></div></td>
<td width="5%" height=35><div align="center">&nbsp;<%= name %></div></td>
<td width="5%"><div align="center">&nbsp;<%= sex %></div></td>
<td width="5%"><div align="center">&nbsp;<%= birthday %></div></td>
<td width="10%"><div align="center">&nbsp;<%= id_card %></div></td>
<td width="8%"><div align="center">&nbsp;<%= province %></div></td>   
     </tr>
<%
}
}
 %>
 </div>
 </td>
 </tr>
</table>
<%
}
catch(Exception e)
{
out.println(e.toString());
}
finally
{
if(dbc!=null)
dbc.close();
}%>