用於查找過期產品數量和類別產品總數的SQL查詢

Question

SQL查詢存在問題。

這是我的產品表：

產品
•ID
•名
•價格
•過期
•fk_category

而且我要的產品編號過期，總數產品分類。

我寫了下面的查詢和我有困難完成它：

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

你能幫助我嗎？

Answer 1

可以在count使用case聲明，只有那些過期：

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