CodeIgniter框架数据库ar类查询分页和总数量的方法

public function pagedata($table_name = '', $where = array(),$like = array(),$page = null,$num = null){
if(empty($table_name)){
return false;
}
/* 获取数量 */
$this->db->select('count(*) AS num');
$this->pagedata_set($table_name,$where,$like);
$query = $this->db->get();
if($query->num_rows() > 0){
$count_result = $query->row_array();
$count = $count_result['num'];
}else{
return null;
}
/* 获取分页数据 */
$this->db->select('*');
$this->pagedata_set($table_name,$where,$like);
if($page != null && $num != null){
$offset = ($page-1)*$num;
$this->db->limit($num,$offset);
}
$query = $this->db->get();

if($query->num_rows() > 0){
$result = $query->result_array();
$return = array();
$return['count'] = $count;
$return['data'] = $result;
var_dump($return);die();
return $return;
}else{
return null;
}
}
/* 查询条件的集合 */
private  function pagedata_set($table_name,$where,$like){
$this->db->from($table_name);
if(!empty($like)){
$this->db->like($like);
}
if(!empty($where)){
$this->db->where($where);
}
$this->db->where('deleted_at', null);
}