MySQL 5.7

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CREATE TABLE events (
id int,
day datetime,
event char(2));
INSERT INTO events VALUES
(1547  ,'2013-05-09 16:26:02','PA'),
(1547  ,'2013-05-15 13:59:23','TA'),
(1547  ,'2013-05-21 10:16:56','EA'),
(1547  ,'2013-05-21 10:17:27','PM'),
(1547  ,'2014-01-16 11:42:12','IH'),
(1547  ,'2014-01-16 11:42:13','RP'),
(1547  ,'2014-01-21 10:01:18','MP'),
(1547  ,'2014-12-05 14:32:21','RE'),
(1547  ,'2014-12-05 14:34:24','RE'),
(1666  ,'2013-05-29 11:26:38','PA'),
(1666  ,'2013-06-04 13:38:42','TA'),
(1666  ,'2013-06-05 14:16:13','EA'),
(1666  ,'2013-08-21 10:07:08','PR'),
(1666  ,'2013-08-21 10:38:51','TR'),
(1666  ,'2013-08-21 10:38:52','MP'),
(1666  ,'2013-10-07 16:26:46','PM'),
(1666  ,'2013-10-09 14:38:51','TM'),
(1666  ,'2013-10-09 14:38:52','EP'),
(1666  ,'2013-10-25 10:29:01','IH'),
(1666  ,'2013-12-13 08:52:41','IH'),
(1666  ,'2013-12-13 08:52:43','RP'),
(1666  ,'2014-01-21 09:55:10','MP'),
(1666  ,'2014-05-05 15:52:34','AB'),
(1666  ,'2014-05-07 14:55:58','RD'),
(1692  ,'2013-06-10 14:17:17','PA'),
(1692  ,'2013-06-10 14:17:53','TA'),
(1692  ,'2013-06-10 15:01:08','EA'),
(1692  ,'2013-08-21 10:04:39','PR'),
(1692  ,'2013-08-21 10:37:38','TR'),
(1692  ,'2013-08-21 10:37:39','ER'),
(1692  ,'2013-09-26 08:33:48','PM'),
(1692  ,'2013-09-26 16:32:46','TM'),
(1692  ,'2013-09-26 16:32:47','EP'),
(1692  ,'2013-10-11 09:21:26','IH'),
(1692  ,'2013-12-19 15:29:20','IV'),
(1692  ,'2013-12-19 15:29:21','RP'),
(1692  ,'2013-12-19 15:33:19','MP'),
(1692  ,'2014-01-21 11:05:46','FX'),
(1692  ,'2014-01-22 10:16:27','RE');

Records: 39  Duplicates: 0  Warnings: 0


select
  id,
  day,
  event
from events 
where event = 'MP'
order by id, day


id
day
event


1547
2014-01-21 10:01:18
MP

1666
2013-08-21 10:38:52
MP

1666
2014-01-21 09:55:10
MP

1692
2013-12-19 15:33:19
MP


SET @quot='';
SET @id=0;
select
  id,
  day,
  lag_day,
  event,
  case when id=lag_id then
     datediff(lag_day,day) end 
     as days_to_next
from
(select
  @id lag_id,
  @id:=id id,
  @quot lag_day, 
  @quot:=day day,
  event
from 
  events
order by 
  id , 
  day desc) e
where event ='MP'
order by
  id,
  day


id
day
lag_day
event
days_to_next


1547
2014-01-21 10:01:18
2014-12-05 14:32:21
MP
318

1666
2013-08-21 10:38:52
2013-10-07 16:26:46
MP
47

1666
2014-01-21 09:55:10
2014-05-05 15:52:34
MP
104

1692
2013-12-19 15:33:19
2014-01-21 11:05:46
MP
33

id	day	event
1547	2014-01-21 10:01:18	MP
1666	2013-08-21 10:38:52	MP
1666	2014-01-21 09:55:10	MP
1692	2013-12-19 15:33:19	MP

id	day	lag_day	event	days_to_next
1547	2014-01-21 10:01:18	2014-12-05 14:32:21	MP	318
1666	2013-08-21 10:38:52	2013-10-07 16:26:46	MP	47
1666	2014-01-21 09:55:10	2014-05-05 15:52:34	MP	104
1692	2013-12-19 15:33:19	2014-01-21 11:05:46	MP	33