sql count（*）查询执行多个结果的另一个查询的结果

Question

如何对执行多个结果的另一个查询的结果执行sql count（*）查询？

我有3张桌子： -

1. user_subscribe表我在哪里＆＃39; user_id＆＃39;和其他专栏。

2. 用户表我们有＆＃39; user_id＆＃39; ＆安培; ＆＃39; COUNTRY_ID＆＃39; user_id与user_subscribe表链接的列和country_id正在与＆＃39; country＆＃39;表

   1. 有country_id＆＃39;的国家/地区表列。

我需要根据属于同一个国家/地区的用户（user_id）获取user_subscribe的总数。 我非常感谢帮助，因为我在过去7天内遇到了这个问题。

Answer 1

SELECT COUNT(US.user_id) as country_user_subscribed
FROM user_subscribe as US
LEFT JOIN users as U ON user.id=US.user_id
LEFT JOIN countries as C on C.id=U.country_id
GROUP BY C.country_id

Answer 2

尝试此解决方案：

SELECT C.CountryName,Count(u.UserId) AS UserCount FROM  User_Subscribe AS us 
LEFT JOIN User AS u ON us.UserId = u.UserId
LEFT JOIN Country AS c ON u.CountryId = c.CountryId
WHERE c.CountryId = 3
GROUP BY c.CountryName