题解 | #商品交易(网易校招笔试真题)#
商品交易(网易校招笔试真题)
http://www.nowcoder.com/practice/f257dfc1b55e42e19eec004aa3cb4174
主要是理解题干：找购买个数超过20,质量小于50的商品，按照商品id升序排序
第一，将两个表进行联结 FROM goods join trans on ...
第二，通过WHERE语句，筛选出“质量小于50的商品”
第三，对goods.id进行GROUP BY 分组，进行聚合求和sum(count),再通过HAVING 筛选出“购买个数超过20”
SELECT g.id,
g.name,
g.weight,
sum(t.count) as total
FROM goods as g JOIN trans as t
ON g.id=t.goods_id
WHERE g.weight<50
GROUP BY g.id
HAVING total>20
ORDER BY g.id;