SQL查找按类别的过期产品数和产品总数

Question

我有一个SQL查询问题。

这是我的产品表：

产品
• ID
• 名称
• 价钱
•已过期
•fk_category

我想要过期的产品数量和按类别分组的产品总数。

我编写以下查询，但很难完成它：

SELECT COUNT(id) as nb_expired, COUNT (id) as nb_product
FROM product
WHERE expired = 1
GROUP BY fk_category;

你能帮我吗？

Answer 1

您可以在count中仅使用一个case语句来过期：

SELECT sum(case when expired = 1 then 1 else 0 end) as nb_expired
,      COUNT (id) as nb_product
FROM   product
GROUP
BY     fk_category

Answer 2

SELECT fk_category, sum(case when expired = 1 then 1 else 0 end) as expired_count,
COUNT (1) as total 
FROM   product 
GROUP BY     fk_category