需要按类别选择5个最新记录？

Question

我需要选择每个品牌类别的五种最新产品，然后显示按类别分组的结果。

MySQL数据库看起来像;

表product：

product_id (pk) 
product_name 
product_etc 
product_publish_date 
brand_id (fk) 

表brand

brand_id (pk) 
brand_name 

结果应该出来像下面...

brand_a product k 
brand_a product a 
brand_a product h 
brand_a product l 
brand_a product 33 

brand_b product h 
brand_b product z 
brand_b product 9 
brand_b product ddd 
brand_b product a 

试图与

Answer 1

尝试：

SELECT p.* 
FROM product p1 
LEFT OUTER JOIN product p2 
    ON (p1.brand_id = p2.brand_id AND p1.product_id < p2.product_id) 
GROUP BY p1.item_id 
HAVING COUNT(*) <= 5 
ORDER BY brand_id, product_publish_date; 

比尔karwin说，这是同样的问题，因为在他的链接 - 我的回答仅仅是回答你的情况的适应。

Answer 2

select brand_name, product_name, count(*) 
from brand 
INNER JOIN product on brand.brand_id = product.brand_id 
order by product_publish_date 
group by brand_name, product_name 
having count(*) <= 5