sql - 分组查询和前n条记录SQL

Question

如果我有一个以列pid, sid作为主键的表，price并且color.

如何创建一个 SQL 查询，该查询可以获取每个pid（产品 ID）color等于的最便宜的价格green？

例如我有行：

(1, 1, 10, "green")
(1, 2, 8, "green")
(1, 3, 11, "green")
(2, 1, 7, "green")
(2, 2, 15, "green")
(2, 3, 22, "green")
(3, 1, 10, "red")
(1, 2, 8, "red")
(1, 3, 11, "red")

然后我会收到 :(1, 2, 8)->pid=1和(2, 1, 7)->pid=2. 不pid=3，因为它的颜色是红色的。

提前致谢。

Answer 1

SELECT pid, min(Price)
from table
Where Color='green'
group by pid

或者，如果您想要整行（并且您的 sql 平台支持排名）...

select * 
from
(
 select *, ROW_NUMBER() over (partition by pid order by price) rn
 from #t
 where color='green'
) v
where rn=1

Answer 2

试试这个，

SELECT  a.*
FROM    tableName a
            INNER JOIN
            (
                SELECT pid, min(price) minPrice
                FROM    tableName b
            ) c ON a.pid = c.pid AND
                    a.price = c.minprice
WHERE   a.color = 'green'