if(!empty($ids)){

//对关系表进行处理

foreach ($binding_tags as $key => $val) {

$arr_past[] = $val['id'];

}

$arr_now = explode(",",$ids);

$len = count($arr_now)-1;

$ids_now = array_slice($arr_now,0,$len);//最终的需要绑定的标签id数组

//对数组做比较

print_r($arr_past);

print_r($ids_now);

//$arr_final = array_diff_assoc($arr_past,$ids_now);

$arr_final = array_merge(array_diff($arr_past,$ids_now),array_diff($ids_now,$arr_past)); //关键

print_r($arr_final );

}