Codeigniter框架实现获取分页数据和总条数的方法

/**
* 获取分页数据及总条数
* @param string @tablename 表名
* @param mixed $where 条件
* @param int $limit 每页条数
* @param int $offset 当前页
*
*/
public function get_page_data($tablename,$where,$limit,$offset,$order_by,$db)
{
??????? if(empty($tablename))
??????? {
??????????? return FALSE;
??????? }
???????
??????? $dbhandle = empty($db) ? $this->db : $db;
???????
??????? if($where)
??????? {
??????????? if(is_array($where))
??????????? {
??????????????? $dbhandle->where($where);
??????????? }
??????????? else
??????????? {
??????????????? $dbhandle->where($where,NULL,false);
??????????? }
??????? }
???????
??????? $db = clone($dbhandle);
??????? $total = $dbhandle->count_all_results($tablename);
???????
??????? if($limit)
??????? {
??????????? $db->limit($limit);
??????? }
???????
??????? if($offset)
??????? {
??????????? $db->offset($offset);
??????? }
???????
??????? if($order_by)
??????? {
??????????? $db->order_by($order_by);
??????? }
???????
??????? $data = $db->get($tablename)->result_array();
???????
??????? return array('total' => $total,'data' => $data);
}