动态菜单

表结构如下：
id,name,pid,sub_menu_name
1,"开发语言",NULL,NULL
2,"开发工具",NULL,NULL
3,"团队名称",NULL,NULL
4,"框架",NULL,NULL
5,NULL,1,"java"
6,NULL,1,"c"
7,NULL,1,"c++"
8,NULL,1,".net"
9,NULL,2,"eclipse"
10,NULL,2,"zend"
11,NULL,2,"myeclipse"
12,NULL,2,"netbeans"
13,NULL,4,"struts"
14,NULL,4,"spring"
15,NULL,4,"webwork"
16,NULL,4,"ibatis"
我现在要把这些数据按关系迭代出来。也就说当我点击：开发语言的时候所以有PID为开发语言ID的子信息查询出来。现在得把这样的信息做成一个菜单的形式，先谢了。