我有3张这样的表:
我必须从中获得以下模式:
category_name->count(product_id)
...
我有一个category_id,我希望在产品表中包含product_id。
我怎样才能做到这一点?
我有以下代码:
SELECT COUNT(p.product_id)
FROM product p
LEFT JOIN product_category_30 pc ON p.product_id = pc.product_id
LEFT JOIN category_30 c ON pc.category_id = c.category_id
OR c.parent_category_id IN(1, 91, 162, 272, 376, 496, 507)
GROUP BY c.category_id
答案 0 :(得分:0)
这样的事情对你有用吗?
SELECT c.name, count(p.product_id)
FROM category_30 c
JOIN product_category_30 pc
ON c.category_id = pc.category_id
JOIN product p
ON pc.product_id = p.product_id
GROUP BY c.name