MySQL 5.7

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CREATE TABLE table1 (id int , userid int , `timestamp` timestamp)
INSERT INTO table1 (id, userid, `timestamp`) VALUES  (1,15,NOW()),
(2,15,NOW() + INTERVAL 1 Minute),(3,15,NOW() + INTERVAL 5 Minute),
(4,22,NOW() + INTERVAL 1 Minute),
(5,22,NOW() + INTERVAL 2 Minute),(6,22,NOW() + INTERVAL 6 Minute),
(7,42,NOW() + INTERVAL 1 Minute),
(8,42,NOW() + INTERVAL 2 Minute),(9,22,NOW() + INTERVAL 7 Minute);
SELECT userid,MAX(`timestamp`) FROM table1 WHERE userid in(15,22,42) GROUP BY userid;


userid
MAX(`timestamp`)


15
2020-03-10 23:49:55

22
2020-03-10 23:51:55

42
2020-03-10 23:46:55


SELECT * FROM table1;


id
userid
timestamp


1
15
2020-03-10 23:44:55

2
15
2020-03-10 23:45:55

3
15
2020-03-10 23:49:55

4
22
2020-03-10 23:45:55

5
22
2020-03-10 23:46:55

6
22
2020-03-10 23:50:55

7
42
2020-03-10 23:45:55

8
42
2020-03-10 23:46:55

9
22
2020-03-10 23:51:55

userid	MAX(`timestamp`)
15	2020-03-10 23:49:55
22	2020-03-10 23:51:55
42	2020-03-10 23:46:55

id	userid	timestamp
1	15	2020-03-10 23:44:55
2	15	2020-03-10 23:45:55
3	15	2020-03-10 23:49:55
4	22	2020-03-10 23:45:55
5	22	2020-03-10 23:46:55
6	22	2020-03-10 23:50:55
7	42	2020-03-10 23:45:55
8	42	2020-03-10 23:46:55
9	22	2020-03-10 23:51:55