Question

这里我有桌子

1）users_interests

user_id    interest_id
677        12
677        14
677        13

2）answer_points

user_id    in_id    point
677        12       -1
677        12       1
677        12       1
677        14       1
678        14       1

3）兴趣

id    name
12    movie
13    cooking
14    music

这里我想做的是，我想要这样的输出

interest_id    name    point
12             movie   1
13             cooking 0
14             music   1

user_id=677

我试过了这个查询

select ui.interest_id,i.name,sum(a.answer_points) as total from
users_interests as ui inner join interests as i on i.id=ui.interest_id
left join answer_points as a on a.in_id=ui.interest_id
where i.user_id='677' group by a.in_id

但不计算1投票。它为电影

返回3 total

Answer 1

试试这个

select id,name,coalesce(find_in_set(id,in_id),0) as points 
from interests i 
left join(select distinct in_id 
from answer_points a where point = 1)a 
on a.in_id = i.id cross join users_interest u 
where u.user_id = 677 group by id;

Answer 2

此代码适用于您的要求，另请查看以下链接

http://rextester.com/NQXE66482

SELECT 
J.interest_id AS 'ID',
I.NAME AS 'NAME',
CASE WHEN K.TOTAL != 0 THEN K.TOTAL
ELSE 0 END AS 'Total'
FROM
users_interests AS J
JOIN
interests AS I
ON
J.interest_id = I.id
LEFT JOIN
(SELECT 
 a.id AS 'ID', 
 a.name AS 'NAME', 
 SUM(b.point) as 'TOTAL'
 FROM 
 interests a 
 LEFT JOIN 
 answer_points b 
 ON a.id = b.in_id
 WHERE user_id = 677
 GROUP BY 1) AS K
 ON
J.interest_id = K.id
WHERE 
J.user_id = 677
GROUP BY 1
ORDER BY 1

Answer 3

您应该使用左连接开始兴趣

select i.id, sum(a.point)
from interests as i 
left users_interests as ui on ui.interest_id = i.id
left join answer_points as a on a.user_id = ui.user_id and a.in_id = i.interest_id
where i.user_id=677
group by a.id

Answer 4

我只需像这样改变JOIN，

select ui.interest_id, i.name, COALESCE(SUM(a.answer_points),0) as total from users_interests as ui
join interests as i on i.id = ui.interest_id
left join answer_points as a on a.in_id = ui.interest_id AND a.user_id = ui.user_id
where ui.user_id='677'
group by a.in_id

我必须在user_id中对join进行比较AND a.user_id = ui.user_id

sum（）返回不正确的值

4 个答案: