帮助SQL查询

Question

可以说我有一张名为"REVIEWS"的表

此表包含客户为各种产品编写的评论.

我希望能够对每个客户编写的所有评论进行"计数",所以我写道:

SELECT count(*) AS counter
FROM reviews 
WHERE customers_id = 12345

现在,我的问题是我希望有一个像上面那样的计数,但仅限于已经编写过SPECIFIC产品评论的客户

例如,

SELECT customers_review
FROM reviews
WHERE
products_id = '170' 

总而言之,我希望能够为他们撰写的每篇评论获得客户总计数,但仅限于为特定产品撰写评论的客户.

非常感谢您的帮助.

Answer 1

select customers_id, count(*)
from reviews
where customers_id in 
(select customers_id from reviews where products_id = '170')
group by customers_id;