SQL如何统计group by后共有几行？

Question

我想要得到group by后共有几行，如图共有12行，应该如何写？

SELECT count(user_order_id),user_order_id FROM `item_order` WHERE seller_id=24 GROUP BY user_order_id ORDER BY user_order_id DESC LIMIT 30 OFFSET 0

Answer 1

在外面再包一层count查询

SELECT count(*) FROM (
    SELECT count(user_order_id),user_order_id FROM `item_order` WHERE seller_id=24 GROUP BY             
    user_order_id ORDER BY user_order_id DESC LIMIT 30 OFFSET 0
);

Answer 2

直接再套一层咯：

SELECT count(*) from (SELECT count(user_order_id),user_order_id FROM `item_order` WHERE seller_id=24 GROUP BY user_order_id ORDER BY user_order_id DESC LIMIT 30 OFFSET 0)

Answer 3

想不通上面的回答为什么都是再套一层!
说说我的理解：SELECT COUNT(DISTINCT user_order_id) FROM item_order WHERE seller_id=24