1. //上一篇 
2.   $front=$Article->where("id<".$id)->order('id desc')->limit('1')->find(); 
3.   $this->assign('front',$front); 
4.   //下一篇 
5.   $after=$Article->where("id>".$id)->order('id desc')->limit('1')->find(); 
6.   $this->assign('after',$after); 
7.  //上一篇 
8. $front=$Classroom->where("nid<".$nid)->order('nid desc')->limit('1')->find(); 
9. $f=!$front?'没有了':'.__URL__.'/nid/'.$front['nid'].'">'.$front['title'].''; 
10. $this->assign('front',$f); 
11. //下一篇 
12. $after=$Classroom->where("nid>".$nid)->order('nid desc')->limit('1')->find(); 
13. $a=!$after?'没有了':'.__URL__.'/nid/'.$after['nid'].'">'.$after['title'].''; 
14. $this->assign('after',$a);