单列COUNT并将其分为2列

Question

这是我的数据库中的“评级”表。

attraction      customer      rate
------------------------------------
attrac1         cust1         like
attrac2         cust1         dislike 
attrac1         cust2         like

我应该编写什么SQL才能使输出变得像这样

attraction      like       dislike
----------------------------------
attrac1           2           0
attrac2           0           1

我试过这个

SELECT a_id,
(SELECT COUNT(rate) FROM rating WHERE rate = 'like') as 'Like',
(SELECT COUNT(rate) FROM rating WHERE rate = 'dislike') as 'Dislike'
FROM rating

但我无法得到我想要的结果。

Answer 1

SELECT  Attraction,
        COUNT(CASE WHEN Rate = 'Like' THEN Customer END) [Like],
        COUNT(CASE WHEN Rate = 'DisLike' THEN Customer END) [DisLike]
FROM    Rating
GROUP BY Attraction

Answer 2

这是一种方法：

SELECT a_id,
    SUM(Case when rate='like' then 1 else 0 end) as 'Like',
    SUM(Case when rate='dislike' then 1 else 0 end) as 'Dislike'
FROM rating
Group BY A_id