mysql查询某个值在分组中出现多次的数据

       场景：一个商品可以按照不同的规格进行售卖，比如玉米，可以一粒装或三粒装等规格进行售卖，现在我想查看有哪些商品是按照多个规格进行售卖的，sql如下所示：

select GROUP_CONCAT(d.specification_id),d.goods_id from 
(select b.specification_id specification_id,b.specification_name specification_name
,c.goods_id goods_id from send_order a join send_order_extend b on a.send_order_id=b.send_order_id join send_order_goods c on a.send_order_id=c.send_order_id
where a.delivery_date='2019-06-25' GROUP BY b.specification_id,c.goods_id) d GROUP BY d.goods_id HAVING count(*)>1