SELECT T1.* FROM
(
SELECT
MAX(no_of_orders) [no_of_orders],
ord.customer_id [customer_id],
ord_dtl.item_id [item_id]
FROM order_main ord
INNER JOIN order_detail ord_dtl
ON ord.order_id = ord_dtl.order_id
GROUP BY
ord.customer_id, ord_dtl.item_id
) T1
INNER JOIN
(
SELECT
MAX(no_of_orders) [no_of_orders],
ord.customer_id
FROM order_main ord
INNER JOIN order_detail ord_dtl
ON ord.order_id = ord_dtl.order_id
GROUP BY
ord.customer_id
) T2
ON
T1.customer_id = T2.customer_id
AND T1.no_of_orders = T2.no_of_orders
我从表 order_main 和 order_detail 中计算出客户订购最多的商品。
我所做的就像我计算了按客户 ID 和商品 ID 分组的订单数量,并将结果集减少为客户订购最多的商品,我通过相同的查询加入了结果集,删除了按商品 ID 的分组。
我觉得这不是一个好的查询。
还有更好的选择吗?
最佳答案
客户订购最多的商品
查询:
SELECT a.no_of_orders,
a.customer_id,
a.item_id
FROM (SELECT
MAX(no_of_orders) [no_of_orders],
ord.customer_id [customer_id],
ord_dtl.item_id [item_id],
ROW_NUMBER() OVER(PARTITION BY ord.customer_id ORDER BY MAX(no_of_orders) DESC) AS rnk
FROM order_main ord
INNER JOIN order_detail ord_dtl
ON ord.order_id = ord_dtl.order_id
GROUP BY
ord.customer_id, ord_dtl.item_id) a
WHERE a.rnk = 1
结果:
| NO_OF_ORDERS | CUSTOMER_ID | ITEM_ID |
---------------|-------------|---------|
| 20 | 2 | 6 |
| 50 | 7 | 6 |
| 1500 | 8 | 7 |
| 10 | 9 | 3 |
关于sql - 如何从按不同项目分组的结果集中计算最大(列)行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18510728/