Mysql查詢獲取每個類別的前5個子類別

Question

我需要一個查詢;條件是：

我想從每個類別中只選擇最新的5個子類別;

當前的查詢是：

SELECT a.id,a.catagory_name,b.id as sucid,b.subcatagory_name 
FROM category a 
LEFT JOIN subcategory b ON a.id = b.catagory_id 
WHERE a.active='y' AND b.active='y' 
ORDER BY a.priority,b.subcatagory_name 

Answer 1

請試試這個。

SELECT a.id,a.catagory_name,b.id as sucid,b.subcatagory_name 
FROM category a 
LEFT JOIN subcategory b ON a.id = b.catagory_id 
WHERE a.active='y' AND b.active='y' 
ORDER BY a.priority,b.category_id DESC 
LIMIT 0,5 

這可能適合你。

Answer 2

讓我們試試這個：

SELECT a.id,a.catagory_name,B.id as sucid,B.subcatagory_name 
FROM category a 
(SELECT id,subcatagory_name FROM subcategory WHERE catagory_id = a.id ORDER BY id DESC LIMIT 5) AS B 
ON a.id = B.catagory_id 
ORDER BY a.priority,B.category_id;