產品taging SQL查詢來獲取其產品3特定的標籤

Question

我有如下3表數據庫設計：

products 
pid pname pprice 

tags 
tag_id tag_name 

products_tag ==> Unique(pid,tag_id) 
pid tag_id 
65 1 
65 3 
66 2 
88 2 
88 4 
88 3 

我有要求取得具有標籤識別= 2，3和4。因此，所有的PID結果在這種情況下是88（pid）。什麼是這個問題陳述的SQL查詢？

Answer 1

select pid 
from products_tag 
where tagid in (2,3,4) 
group by pid 
having count(tagid) = 3 

Answer 2

使用條件COUNT

SELECT PID, COUNT(CASE WHEN tag_id IN (2,3,4) THEN 1 END) as total 
FROM products_tag 
GROUP BY PID 
HAVING COUNT(CASE WHEN tag_id IN (2,3,4) THEN 1 END) = 3