mysql - 返回图像上喜欢和不喜欢的计数

Question

我的表包含 img_id 和 likes 列。示例:

 1  1
 1  1
 1  0
 2  0
 2  0
 3  1

所以当运行这个查询时:

select img_id, count(likes)
from my_table
where likes = 1
group by img_id

结果如下:

1  2
3  1

当我运行时:

select img_id, count(likes)
from my_table
where likes = 0
group by img_id

结果是:

1 1
2 2

我的问题是:

我如何在 query1 中返回 img_id 2 = 0 ，我的意思是 img_id = 2 没有喜欢同样在查询 2 img_id = 3 中没有不喜欢所以我需要返回 3 -> 0

Answer 1

在 MySQL 和 SQL Server 中，

SELECT  img_id,
        SUM(CASE WHEN likes = 1 THEN 1 ELSE 0 END) totalLikes,
        SUM(CASE WHEN likes = 0 THEN 1 ELSE 0 END) totalDisLikes
FROM    tableName
GROUP   BY img_ID

或者简单地在 MySQL 中，

SELECT  img_id,
        SUM(likes = 1) totalLikes,
        SUM(likes = 0) totalDisLikes
FROM    tableName
GROUP   BY img_ID

• SQLFiddle Demo (BOTH)