Question

我在表格中有以下数据：

ORDERID, PRODUCT,  QUANTITY
1,       potatoes, 10
1,       oranges,  20
2,       apples,   10
2,       oranges,  15
3,       pears,    20
3,       peaches,  12

我想查询该表以过滤掉重复的产品（例如橙子），只获取最新的（更高的ORDERID）值。这应该导致：

ORDERID, PRODUCT,  QUANTITY
1,       potatoes, 10
2,       apples,   10
2,       oranges,  15
3,       pears,    20
3,       peaches,  12

Answer 1

select  *

from   (select      t.*
                   ,row_number () over (partition by PRODUCT order by ORDERID desc) as rn

        from        mytable t
        )

where   rn = 1

Answer 2

@Dudu给出的答案的替代方法是查询子查询以查找每个产品的最大订单ID，然后将其连接回原始表格以限制您想要查看的记录。

SELECT t1.ORDERID,
       t1.PRODUCT,
       t1.QUANTITY
FROM yourTable t1
INNER JOIN
(
    SELECT PRODUCT, MAX(ORDERID) AS MAX_ORDERID
    FROM yourTable
    GROUP BY PRODUCT
) t2
    ON t1.PRODUCT = t2.PRODUCT AND
       t1.ORDERID = t2.MAX_ORDERID

过滤行以仅获取最新值

2 个答案: