php - mysql multiple COUNT() from multiple tables with LEFT JOIN

Question

我想展示所有用户的结论。

我有 3 个表。

表格帖子

post_id(index)     user_id
1                  1
2                  3
3                  3
4                  4

table 照片

photo_id(index)     user_id
1                   2
2                   4
3                   1
4                   1

表格视频

photo_id(index)     user_id
1                   4
2                   4
3                   3
4                   3

和表用户

user_id(index)     user_name
1                  mark
2                  tommy
3                  john
4                  james

事实上，每个表都有超过 4 行。

我想要这样的结果。

id     name      post    photo   videos
1      mark      1       2       0
2      tommy     0       1       0
3      john      2       0       2
4      james     1       1       2
5      ..        ..      ..      ..

下面的代码是可以正常工作但速度很慢的 SQL，如果你能帮助我如何使用 LEFT JOIN，我将不胜感激。谢谢。

SQL

"select user.*, 
(select count(*) from post where post.userid = user.userid) postCount,
(select count(*) from photo where photo.userid = user.userid) photoCount,
(select count(*) from video where video .userid = user.userid) videoCount
from user order by user.id"

(或根据需要按 postCount、photoCount 或 videoCount ASC 或 DESC 排序)

我之前做过研究，但没有任何帮助。

Answer 1

    SELECT u.user_id, 
           u.user_name,
           COUNT(DISTINCT p.post_id) AS `postCount`,
           COUNT(DISTINCT ph.photo_id) AS `photoCount`,
           COUNT(DISTINCT v.video_id) AS `videoCount`
      FROM user u
 LEFT JOIN post p
        ON p.user_id = u.user_id
 LEFT JOIN photo ph
        ON ph.user_id = u.user_id
 LEFT JOIN video v
        ON v.user_id = u.user_id
  GROUP BY u.user_id
  ORDER BY postCount;

Live DEMO