Select returns 只有新的状态变化

Question

我想select所有在2020年12月状态变为B1状态的账户。即现在有B1状态而之前记录中没有的账户。 VALID_TO_DATE = 31/12/2100 (DD/MM/YYYY) 的记录是最近的记录。

但是也有一些情况，比如账号400，状态变化发生在倒数第二条记录，不再有效。但是因为是12月份的变化，状态和有效记录一样，所以我的select statement 必须包含account 400.

期望的结果： 从这个意义上说，根据下面的数据，我需要一个 select 而 returns 只需要 100和 400

ROW	ACCOUNT_ID	ACCOUNT_CHANGE_DATE	VALID_TO_DATE	ACCOUNT_STATUS
1	100	21/10/2020	05/12/2020	A1
2	100	05/12/2020	15/12/2020	A1
3	100	15/12/2020	31/12/2100	B1
4	200	09/11/2020	22/12/2020	A1
5	200	22/12/2020	25/12/2020	A1
6	200	25/12/2020	31/12/2100	A1
7	300	11/11/2020	19/11/2020	B1
8	300	19/11/2020	23/12/2020	A1
9	300	23/12/2020	31/12/2100	A1
10	400	16/11/2020	14/12/2020	A1
11	400	14/12/2020	18/12/2020	B1
12	400	18/12/2020	31/12/2100	B1

我的消息来源 table 记录了影响每个帐户的所有更改，这些更改可能会或可能不会更改相应帐户的状态。

这是我的 incomplete/wrong 尝试：

SELECT ACCOUNT_ID
FROM TABLE t1
where ACCOUNT_STATUS ="B1"
      AND ACCOUNT_CHANGE_DATE BETWEEN '01/12/2020' AND '31/12/2020' 
      AND VALID_TO_DATE = '31/12/2100'
      AND NOT EXISTS (SELECT * FROM TABLE t2
                      WHERE t2.ACCOUNT_ID = t1.ACCOUNT_ID 
                            AND t2.ACCOUNT_STATUS = 'B1' 
                            AND t2.ACCOUNT_CHANGE_DATE < t1.ACCOUNT_CHANGE_DATE);

Answer 1

I would like to select all the accounts that status changed to B1 during the month of December 2020.

使用lag():

select t1.*
from (select t1.*,
             lag(status) over (partition by account_id order by ACCOUNT_CHANGE_DATE) as prev_status
      from t1
     ) t1
where prev_status <> 'B1' and status = 'B1' and
      account_change_date >= '2021-12-01' and
      account_change_date < '2022-01-01'

Select returns 只有新的状态变化

Select that returns only new status changes

sql

select

subquery

relational-database

where-clause