如何样联动实现下拉列表框取值

怎么样联动实现下拉列表框取值?
继上次的提问:
我在做用户权限维护时,思路是这样的:
1、用户权限表两个字段:userid   ,   roleid。
2、userid我从用户表里将所有记录取出,传给第一个下拉列表框。
3、之后我想选中一个用户后,将该用户未选的权限显示在第二个下拉列表框,已选的权限显示在第三个下拉列表框。

第二步的脚本如下:
<tr   class= "common ">  
   
<td   width= "12% "> <bean:message   key= "userRole.lable.userName "/> </td>
<td   width= "38% "   class= "contain ">
<html:select   property= "userId "     onchange= "selectUser(this.value) ">   -->
<bean:message   key= "common.label.select "/>
<logic:iterate   id= "user "   name= "userRows ">
<option   value= " <bean:write   name= "user "   property= "value "/> "> <bean:write   name= "user "   property= "label "/> </option>
</logic:iterate>

</html:select>
</td>
</tr>
<tr   class= "common ">  
<td   width= "12% "> <bean:message   key= "userRole.lable.role "/> </td>
<td   width= "38% "   class= "contain "   colspan= "4 ">
<table   width= "100% "   height= "106 "   border= "0 "   class= "abc ">
                    <tr>  
                        <td   width= "22% "   height= "102 "   align= "left "   valign= "top ">   <p> <bean:message   key= "userRole.role.waitToChoice "/> <br>
<html:select   property= "waitChoiceRole "   size= "6 "   style= "width:220 ">
<logic:iterate   id= "waitChoiceRoleId "   name= "waitChoiceRoleRows ">
<option   value= " <bean:write   name= "waitChoiceRoleId "   property= "value "/> "> <bean:write   name= "waitChoiceRoleId "   property= "label "/> </option>
</logic:iterate>
</html:select>
                            </p> </td>
                            <td   width= "14% "   align= "center "   valign= "top ">   <p> <br>
                                <input   type=button   name= "button4 "   style= "width:25 "   value= " <bean:message   key= "common.button.addAll "/> "   onclick= "typeAppAddAll() ">
                                <br/>
                                <input   type=button   name= "button3 "   style= "width:25 "   value= " <bean:message   key= "common.button.addOne "/> "   onclick= "typeAppAddOne() ">