MYSQL将两个表与自己创建的列合并

Question

嗨，我对这两个表有两个不同的查询，如下所示：

表1：

表2：

[1] select exerciseId, sum(frustrated = 'Y') as Frustrated,
sum(frustrated = 'N') as NotFrustrated
from selfreportfrustration
group by exerciseId;

和

[2] SELECT exercisesId, count(*) as total FROM exerciseprogress GROUP BY 
exercisesId;

如何将这两个查询合并为一个查询，这样我就可以拥有一个包含4列的单一视图？如果我没记错的话，exerciseId和ExercisesId都是相同的，因此可以将它们加入。谢谢您的时间！

Answer 1

使用左联接

select a.*, b.total 
from

(select exerciseId, sum(frustrated = 'Y') as Frustrated,
sum(frustrated = 'N') as NotFrustrated
from selfreportfrustration
group by exerciseId) a 

left join 
(SELECT exercisesId, count(*) as total FROM exerciseprogress GROUP BY 
exercisesId) b 
on a.exerciseId=b.exercisesId

Answer 2

这是一个查询：

select main.exerciseId, sum(main.frustrated = 'Y') as Frustrated,sum(main.frustrated = 'N') as NotFrustrated,
(SELECT count(*) FROM exerciseprogress WHERE exercisesId = main.exerciseId) as total
from selfreportfrustration AS main
group by exerciseId;