MySQL查找每个用户的帖子总数 [英] MySQL Find the total amount of posts per user

问题描述

我有一个包含以下两个表的数据库， USERS，POSTS 我正在寻找一种方法来获取用户拥有多少帖子的计数.

I have a Database with the following two tables, USERS, POSTS I am looking for a way to get the count of how many posts a user has.

Users            Posts
+----+------+    +----+---------+-----------+
| ID | Name |    | ID | user_id | Name      |
+----+------+    +----+---------+-----------+
| 1  | Bob  |    | 1  | 1       | Blargg... | 
+----+------+    +----+---------+-----------+
| 2  | Jim  |    | 2  | 1       | Blargg... | 
+----+------+    +----+---------+-----------+
| 3  | Jo   |    | 3  | 2       | Blargg... | 
+----+------+    +----+---------+-----------+

我尝试了以下SQL命令的许多变体，但均未成功.与其显示单个用户的帖子数，不如显示一行包含所有帖子的数.

I have tried many variations of the following SQL command with out any success. instead of showing the count of posts for a single user it shows a single row with all the posts as the count.

SELECT users.* , COUNT( Posts.user_id ) 
FROM users
LEFT JOIN Posts ON users.id = Posts.user_id

最后我想要这样的东西

+----+------+ 
| ID | Count|
+----+------+
| 1  |  2   |  
+----+------+
| 2  |  1   |  
+----+------+

推荐答案

弄清楚了. 自嘲

SELECT users.*, count( posts.user_id ) 
FROM posts LEFT JOIN users ON users.id=posts.user_id 
GROUP BY posts.user_id

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