Select row with most recent date per location and increment recent date by 1 for each row by location using MariaDB - sql

Question

I have a table of location which has 'Date column'. I have to find recent date by each group of locationID for e.g. locationID 1 has most recent date '31 May 2022'. After finding recent date from the group of locationID I have to add 14 days in that recent date and store it in NewDate column. and add + 1 in that new date for other row for that group of locationID.
My table is:
id locationID Date NewDate
1 1 31 May 2022
2 1 16 May 2022
3 1 28 Apr 2021
4 2 29 Mar 2022
5 2 22 Feb 2022
6 3 14 Jun 2022
7 3 27 Oct 2021
8 4 01 Feb 2022
9 4 04 May 2022
10 4 14 Jun 2021
11 5 01 Jun 2022
12 5 29 May 2022
13 5 20 Sep 2022
14 5 11 Aug 2022
15 5 03 Aug 2022
Answer should be as below:
For e.g. for locationID = 1
id locationID Date NewDate
1 1 31 May 2022 14 Jun 2022 // Recent Date + 14 Days - 31 May + 14 Days
2 1 16 May 2022 15 Jun 2022 // Recent Date + 15 Days - 31 May + 15 Days
3 1 28 Apr 2021 16 Jun 2022 // Recent Date + 16 Days - 31 May + 16 Days
I have come across few similar post and found recent date like this:
SELECT L.*
FROM Locations L
INNER JOIN
(SELECT locationID, MAX(Date) AS MAXdate
FROM Locations
GROUP BY locationID) groupedL
ON L.locationID = groupedL.locationID
AND L.Date = groupedL.MAXdate
using above code I am able to find recent date per location but how do I add and increment required days and store it to NewDate column ? I am new to MariaDB, please suggest similar post link, any reference documents or blogs. Should I make some function to perform this logic and call the function to store required dates in NewDate column? I am not sure please suggest. Thank you.
RESULT SHOULD LOOK LIKE BELOW:
id locationID Date NewDate
1 1 31 May 2022 14 Jun 2022 // Recent Date for locationid 1 + 14 Days - 31 May + 14 Days
2 1 16 May 2022 15 Jun 2022 // Recent Date for locationid 1 + 15 Days - 31 May + 15 Days
3 1 28 Apr 2021 16 Jun 2022 // Recent Date for locationid 1 + 16 Days - 31 May + 16 Days
4 2 29 Mar 2022 12 APR 2022 // Recent Date for locationid 2 + 14 Days
5 2 22 Feb 2022 13 APR 2022 // Recent Date for locationid 2 + 15 Days
6 3 14 Jun 2022 28 JUN 2022 // Recent Date for locationid 3 + 14 Days
7 3 27 Oct 2021 29 JUN 2022 // Recent Date for locationid 3 + 15 Days
8 4 01 Feb 2022 18 MAY 2022 // Recent Date for locationid 4 + 14 Days
9 4 04 May 2022 19 MAY 2022 // Recent Date for locationid 4 + 15 Days
10 4 14 Jun 2021 20 MAY 2022 // Recent Date for locationid 4 + 16 Days
11 5 01 Jun 2022 04 OCT 2022 // Recent Date for locationid 5 + 14 Days
12 5 29 May 2022 05 OCT 2022 // Recent Date for locationid 5 + 15 Days
13 5 20 Sep 2022 06 OCT 2022 // Recent Date for locationid 5 + 16 Days
14 5 11 Aug 2022 07 OCT 2022 // Recent Date for locationid 5 + 17 Days
15 5 03 Aug 2022 08 OCT 2022 // Recent Date for locationid 5 + 18 Days

Answer 1

You can use a cte:
with cte as (
select l1.*, l2.m, (select sum(l4.id < l1.id and l4.locationid = l1.locationid) from locations l4) inc from locations l1
join (select l3.locationid, max(l3.dt) m from locations l3 group by l3.locationid) l2 on l1.locationid = l2.locationid
)
select c.id, c.locationid, c.dt, c.m + interval 14 + c.inc day from cte c

Answer 2

You could use analytic window functions and update the original table by joining to a sub-query (works for MariaDB):
update t
join (
select Id,
Date_Add(First_Value(date) over(partition by locationId order by date desc),
interval (13 + row_number() over(partition by locationId order by date desc)) day
) NewDate
from t
)nd on t.id = nd.id
set t.Newdate = nd.NewDate;
See DB<>Fiddle example