如何在第三个变量mysql查询中求和两个子查询的总和？

Question

I am trying to sum total likes and comments but result is always zero (0) please help me to resolve this issue because i have implemented mostly solutions that I find but no success.

SELECT DISTINCT id,name,picture,
(SELECT COUNT(id) from likes) as likes,
(SELECT COUNT(id) from comments) as comments,
(likes+comments) as total
From users

Answer 1

You cannot use column aliases in the same SELECT where they are defined. I would suggest doing this in the FROM clause:

SELECT DISTINCT u.id, u.name, u.picture, l.likes, c.comments,
       (l.likes + c.comments) as total
FROM users u CROSS JOIN
     (SELECT COUNT(id) as likes FROM likes) l CROSS JOIN
     (SELECT COUNT(id) as comments FROM comments) c;

Presumably, u.id is unique. If so, you should drop the SELECT DISTINCT . It just adversely affects performance.

Answer 2

You can try like this

SELECT DISTINCT id,name,picture,
(SELECT COUNT(id) from likes) as likes,
(SELECT COUNT(id) from comments) as comments,
(SELECT COUNT(id) from likes)+(SELECT COUNT(id) from comments) as total
From users