subtract multiple dates within one id - mysql

Question

I'm trying to accomplish something in mySQL, which is difficult due to the lack of a "lag" function and because of all the examples I've read regarding date differences, since in all those examples there's always one ID to one date. In here, I am trying to do the date differences within an ID, and when the date difference is over 60, then returning an indicator of 1, else 0.
Not sure what the best way is to go about this. Would it be some combination of using row_number() with the date? The snag is doing this within multiple IDs, as a lot of things I read don't cover that. Any direction would be helpful.
Thanks!
ID | Service Date | Date Difference | Indicator
1 | 1/22/2016 | 0 | 1
1 | 3/26/2016 | 64 | 1
1 | 5/25/2016 | 60 | 0
1 | 9/15/2016 | 113 | 1
2 | 8/1/2016 | 0 | 1
3 | 1/26/2016 | 0 | 1
3 | 3/9/2016 | 43 | 0
3 | 4/30/2016 | 52 | 0
4 | 8/9/2016 | 0 | 1
5 | 11/19/2016 | 0 | 1
6 | 10/14/2016 | 0 | 1
7 | 1/31/2016 | 0 | 1
7 | 8/11/2016 | 193 | 1

Answer 1

You can use variables, but this is tricky. For this to work reliably, all the variables need to be assigned in a single expression:
select t.*, datediff(prev_date, date) as diff,
(case when datediff(prev_date, date) < 60 then 0 else 1 end) as indicator
from (select t.*,
(case when #id = id
then (case when (#prev := #d) = NULL then 'never' -- intentional
when (#d := date) = NULL then 'never' -- intentional
else #prev
end)
when (#d := date) = NULL then 'never' -- intentional
else NULL
end) as prev_date
from t cross join
(select #id := -1, #d := '') params
order by id, date
) t

Answer 2

create view id_and_date as
select id, service_date from your table;
create view id_and_date_and_prior as
select
a.id, a.service_date,
coalesce(
(select max(b.service_date) from id_and_date b
where b.id = a.id and b.service_date < a.service_date),
a.service_date)
as prior_date
from id_and_date a
select a.id, a.service_date, a.prior_date
date_diff(a.service_date, a.prior_date) as diff,
case when date_diff(a.service_date, a.prior_date) > 60
then 1 else 0 end
as indicator
from id_and_date_and_prior a

Answer 3

Posting to simplify and correct the function calls from the answer provided by #tpdi. Please accept/upvote their answer, as this was pretty much copied from it.
Changes:
date_diff to DATEDIFF
removed create view calls in favor of subquery of t
assigned variable to the diff value
indicator of 0 on initial value as 0 diff to 1
replaced when case in favor of IF
SELECT
c.id,
c.service_date,
#diff := DATEDIFF(c.service_date, c.prior_date) AS diff,
IF(#diff = 0 || #diff > 60, 1, 0) AS indicator
FROM (
SELECT
a.id,
a.service_date,
COALESCE(
(SELECT MAX(b.service_date)
FROM t AS b
WHERE b.id = a.id
AND b.service_date < a.service_date),
a.service_date
) AS prior_date
FROM t AS a
) AS c;
Will result in:
| id | service_date | diff | indicator |
| 1 | 2016-01-22 | 0 | 1 |
| 1 | 2016-03-26 | 64 | 1 |
| 1 | 2016-05-25 | 60 | 0 |
| 1 | 2016-09-15 | 113 | 1 |
| 2 | 2016-08-01 | 0 | 1 |
| 3 | 2016-01-26 | 0 | 1 |
| 3 | 2016-03-09 | 43 | 0 |
| 3 | 2016-04-30 | 52 | 0 |
| 4 | 2016-08-09 | 0 | 1 |
| 5 | 2016-11-19 | 0 | 1 |
| 6 | 2016-10-14 | 0 | 1 |
| 7 | 2016-01-31 | 0 | 1 |
| 7 | 2016-08-11 | 193 | 1 |