SQL面试题练习 —— 查询最近一笔有效订单
目录
- 1 题目
- 2 建表语句
- 3 题解
题目来源：字节跳动。
1 题目
现有订单表t_order，包含订单ID，订单时间,下单用户，当前订单是否有效，请查询出每个用户每笔订单的上一笔有效订单
+---------+----------------------+----------+-----------+
| ord_id | ord_time | user_id | is_valid |
+---------+----------------------+----------+-----------+
| 1 | 2023-12-11 12:01:03 | a | 1 |
| 2 | 2023-12-11 12:02:06 | a | 0 |
| 3 | 2023-12-11 12:03:15 | a | 0 |
| 4 | 2023-12-11 12:04:20 | a | 1 |
| 5 | 2023-12-11 12:05:03 | a | 1 |
| 6 | 2023-12-11 12:01:02 | b | 1 |
| 7 | 2023-12-11 12:03:03 | b | 0 |
| 8 | 2023-12-11 12:04:01 | b | 1 |
| 9 | 2023-12-11 12:07:03 | b | 1 |
+---------+----------------------+----------+-----------+
期望查询结果如下：
+---------+----------------------+----------+-----------+--------------------+
| ord_id | ord_time | user_id | is_valid | last_valid_ord_id |
+---------+----------------------+----------+-----------+--------------------+
| 1 | 2023-12-11 12:01:03 | a | 1 | NULL |
| 2 | 2023-12-11 12:02:06 | a | 0 | 1 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 1 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 6 | 2023-12-11 12:01:02 | b | 1 | NULL |
| 7 | 2023-12-11 12:03:03 | b | 0 | 6 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 6 |
| 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
+---------+----------------------+----------+-----------+--------------------+
2 建表语句
--建表语句
create table t_order
(
ord_id bigint COMMENT '订单ID',
ord_time string COMMENT '订单时间',
user_id string COMMENT '用户',
is_valid bigint COMMENT '订单是否有效'
) COMMENT '订单记录表'
stored as orc
;
-- 数据插入
insert into t_order(ord_id,ord_time,user_id,is_valid)
values
(1,'2023-12-11 12:01:03','a',1),
(2,'2023-12-11 12:02:06','a',0),
(3,'2023-12-11 12:03:15','a',0),
(4,'2023-12-11 12:04:20','a',1),
(5,'2023-12-11 12:05:03','a',1),
(6,'2023-12-11 12:01:02','b',1),
(7,'2023-12-11 12:03:03','b',0),
(8,'2023-12-11 12:04:01','b',1),
(9,'2023-12-11 12:07:03','b',1);
3 题解
（1）先查询出有效订单，然后计算出每笔有效订单的上一单有效订单；
select ord_id,ord_time,user_id,is_valid,lag(ord_id) over (partition by user_id order by ord_time asc) as last_valid_ord_id
from (select ord_id,ord_time,user_id,is_validfrom t_orderwhere is_valid = 1) t
执行结果
+---------+----------------------+----------+-----------+--------------------+
| ord_id | ord_time | user_id | is_valid | last_valid_ord_id |
+---------+----------------------+----------+-----------+--------------------+
| 1 | 2023-12-11 12:01:03 | a | 1 | NULL |
| 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 6 | 2023-12-11 12:01:02 | b | 1 | NULL |
| 8 | 2023-12-11 12:04:01 | b | 1 | 6 |
| 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
+---------+----------------------+----------+-----------+--------------------+
（2）原始的明细数据与新的有效订单表按照用户进行关联，有效订单表的订单时间大于等于原始订单表；
with tmp as (-- 有效订单及其上一单有效记录select ord_id,ord_time,user_id,is_valid,lag(ord_id) over (partition by user_id order by ord_time asc) as last_valid_ord_idfrom (select ord_id,ord_time,user_id,is_validfrom t_orderwhere is_valid = 1) t)
select t1.*,t2.*
from t_order t1
left join tmp t2
on t1.user_id = t2.user_id
where t1.ord_time <= t2.ord_time
执行结果
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+
| t1.ord_id | t1.ord_time | t1.user_id | t1.is_valid | t2.ord_id | t2.ord_time | t2.user_id | t2.is_valid | t2.last_valid_ord_id |
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+
| 1 | 2023-12-11 12:01:03 | a | 1 | 1 | 2023-12-11 12:01:03 | a | 1 | NULL |
| 1 | 2023-12-11 12:01:03 | a | 1 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 2 | 2023-12-11 12:02:06 | a | 0 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 |
| 1 | 2023-12-11 12:01:03 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 2 | 2023-12-11 12:02:06 | a | 0 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 5 | 2023-12-11 12:05:03 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 |
| 6 | 2023-12-11 12:01:02 | b | 1 | 6 | 2023-12-11 12:01:02 | b | 1 | NULL |
| 6 | 2023-12-11 12:01:02 | b | 1 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 |
| 7 | 2023-12-11 12:03:03 | b | 0 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 |
| 6 | 2023-12-11 12:01:02 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
| 7 | 2023-12-11 12:03:03 | b | 0 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
| 9 | 2023-12-11 12:07:03 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 |
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+
（3）使用row_number，原始订单记录表中的user_id、ord_id进行分组，按照有效订单表的时间排序，增加分组排序
with tmp as (-- 有效订单及其上一单有效记录select ord_id,ord_time,user_id,is_valid,lag(ord_id) over (partition by user_id order by ord_time asc) as last_valid_ord_idfrom (select ord_id,ord_time,user_id,is_validfrom t_orderwhere is_valid = 1) t)
select t1.*,t2.*,row_number() over (partition by t1.ord_id,t1.user_id order by t2.ord_time asc) as rn
from t_order t1
left join tmp t2
on t1.user_id = t2.user_id
where t1.ord_time <= t2.ord_time
执行结果
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+-----+
| t1.ord_id | t1.ord_time | t1.user_id | t1.is_valid | t2.ord_id | t2.ord_time | t2.user_id | t2.is_valid | t2.last_valid_ord_id | rn |
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+-----+
| 1 | 2023-12-11 12:01:03 | a | 1 | 1 | 2023-12-11 12:01:03 | a | 1 | NULL | 1 |
| 1 | 2023-12-11 12:01:03 | a | 1 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 | 2 |
| 1 | 2023-12-11 12:01:03 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 3 |
| 2 | 2023-12-11 12:02:06 | a | 0 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 | 1 |
| 2 | 2023-12-11 12:02:06 | a | 0 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 2 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 | 1 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 2 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 4 | 2023-12-11 12:04:20 | a | 1 | 1 | 1 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 2 |
| 5 | 2023-12-11 12:05:03 | a | 1 | 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 1 |
| 6 | 2023-12-11 12:01:02 | b | 1 | 6 | 2023-12-11 12:01:02 | b | 1 | NULL | 1 |
| 6 | 2023-12-11 12:01:02 | b | 1 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 | 2 |
| 6 | 2023-12-11 12:01:02 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 | 3 |
| 7 | 2023-12-11 12:03:03 | b | 0 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 | 1 |
| 7 | 2023-12-11 12:03:03 | b | 0 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 | 2 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 8 | 2023-12-11 12:04:01 | b | 1 | 6 | 1 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 | 2 |
| 9 | 2023-12-11 12:07:03 | b | 1 | 9 | 2023-12-11 12:07:03 | b | 1 | 8 | 1 |
+------------+----------------------+-------------+--------------+------------+----------------------+-------------+--------------+-----------------------+-----+
（4）去除冗余字段，筛选rn=1 的记录
with tmp as (-- 有效订单及其上一单有效记录select ord_id,ord_time,user_id,is_valid,lag(ord_id) over (partition by user_id order by ord_time asc) as last_valid_ord_idfrom (select ord_id,ord_time,user_id,is_validfrom t_orderwhere is_valid = 1) t)
select *
from (select t1.*,t2.last_valid_ord_id,row_number() over (partition by t1.ord_id,t1.user_id order by t2.ord_time asc) as rnfrom t_order t1left join tmp t2on t1.user_id = t2.user_idwhere t1.ord_time <= t2.ord_time) tt
where rn = 1
执行结果
+------------+----------------------+-------------+--------------+-----------------------+--------+
| tt.ord_id | tt.ord_time | tt.user_id | tt.is_valid | tt.last_valid_ord_id | tt.rn |
+------------+----------------------+-------------+--------------+-----------------------+--------+
| 1 | 2023-12-11 12:01:03 | a | 1 | NULL | 1 |
| 2 | 2023-12-11 12:02:06 | a | 0 | 1 | 1 |
| 3 | 2023-12-11 12:03:15 | a | 0 | 1 | 1 |
| 4 | 2023-12-11 12:04:20 | a | 1 | 1 | 1 |
| 5 | 2023-12-11 12:05:03 | a | 1 | 4 | 1 |
| 6 | 2023-12-11 12:01:02 | b | 1 | NULL | 1 |
| 7 | 2023-12-11 12:03:03 | b | 0 | 6 | 1 |
| 8 | 2023-12-11 12:04:01 | b | 1 | 6 | 1 |
| 9 | 2023-12-11 12:07:03 | b | 1 | 8 | 1 |
+------------+----------------------+-------------+--------------+-----------------------+--------+