End date with null value :db2-sql

Question

i have a table my_date

id        Start          END
1       2021-01-13     2021-04-15
1       2021-04-16     2021-11-28
1       2021-11-29        null
2       2021-05-05     2021-09-13
2       2021-09-13     2021-12-31
3       2020-01-09     2021-08-29
3       2021-08-30     2023-04-15

what i want to want to choose the id that have max(end)<= 2021-12-31 so my result should be just

id        Start          END
2       2021-09-13     2021-12-31

Answer 1

You can filter by the date limit, then order by date in descending manner, and finally retrieve the first row only.

For example:

select *
from t
where end <= date '2021-12-31'
order by end desc
fetch next 1 rows only

Result:

ID  START       END
--  ----------  ----------
 2  2021-09-13  2021-12-31

See running example at db<>fiddle .

Answer 2

Try this:

SELECT id, Start, END
FROM
(
SELECT *
, ROW_NUMBER () OVER (PARTITION BY ID ORDER BY Start DESC) AS RN_
FROM
(
VALUES
  (1, '2021-01-13', '2021-04-15')
, (1, '2021-04-16', '2021-11-28')
, (1, '2021-11-29', null)
, (2, '2021-05-05', '2021-09-13')
, (2, '2021-09-13', '2021-12-31')
, (3, '2020-01-09', '2021-08-29')
, (3, '2021-08-30', '2023-04-15')
) T (id, Start, END)
) T
WHERE RN_ = 1 AND END <= '2021-12-31'

dbfiddle link