鉴于两个用户，选择每一个岗位两个用户评级，并且每个用户的每一个朝后

Question

说我有如下表评级：

create table ratings (
user_id int unsigned not null, 
post_id int unsigned not null, 
rating set('like','dislike'), 
primary key (user_id, post_id) 
); 

和两个用户，IDS 1和2。我想要了解他们在评分中的赞同程度，所以我需要的是一种选择两位用户评分的所有帖子的方式，以及每位用户对每篇帖子的评分。例如：

+---------+---------+---------+ 
| post_id | rating1 | rating2 | 
+---------+---------+---------+ 
|  1 | like | dislike | 
|  2 | like | like | 
|  5 | like | dislike | 
|  6 | dislike | dislike | 
+---------+---------+---------+ 

任何线索表示赞赏，谢谢！

Answer 1

加入您的评级表上本身的帖子ID内，并从每个表中选择等级，限制用户：

SELECT r1.post_id, r1.rating AS rating1, r2.rating AS rating2 
FROM ratings r1 
JOIN ratings r2 ON r1.post_id=r2.post_id AND r1.user_id!=r2.user_id 
WHERE r1.user_id=1 AND r2.user_id=2