##1. 分页原理：

limit offset, sizeoffset:偏移量  offset=(当前页-1）*sizesize:每页显示条数

#2. 排序

order by ‘排序字段’ ‘正序或反序'

3. demo

$doctor=M('freegoods');       $num=I('page','1','intval');//当前页码     $pagesize=I('size','5','intval');//每页显示条数       $count=$doctor->count();//总条数       $sort=I('sort','id');//当         $order=I('order','asc');       $totalpage = ceil($count/$pagesize);//总页数        $offset = ($num-1)*$pagesize;   $sql = "select id,doctorname,post,asktime,skill,storecode,gender,userimg from hx_doctor order by $sort $order  limit $offset,$pagesize ";        $info=$doctor->query($sql);