I have the following table that is created by this code

CREATE TABLE enrollments (
person_id INT,
date DATE,
duration int);

INSERT INTO enrollments (person_id, date, duration)
VALUES
(1, '2004-01-01', 35),
(1, '2004-01-15', 60),
(1, '2004-02-01', 15),
(1, '2004-09-01', 30),
(2, '1994-01-18', 30),
(2, '1994-03-01', 30);

The table looks like:

person_id   date     duration
        1   2004-01-01  35
        1   2004-01-15  60
        1   2004-02-01  15
        1   2004-09-01  30
        2   1994-01-18  30
        2   1994-03-01  30

I’d like to apply the following logic:

Person 1:

Row 1: 2004-01-01, 35 (no previous row to compare with)

Row 2: 2004-01-15, 60

Previous date + previous duration: 2004-01-01 + 35 days = 2004-02-05. Compare this date with the next row’s date:

Since 2004-02-05 > 2004-01-15, update 2004-01-15 to 2004-02-05

Row 3: 2004-02-01, 15

Previous date + previous duration: 2004-02-05 + 60 days = 2004-04-05

Since 2004-04-05 > 2004-02-01, update 2004-02-01 to 2004-04-05

Row 4: 2004-09-01, 30

Previous date + previous duration: 2004-04-05 + 15 days = 2004-04-20

Since 2004-04-20 < 2004-09-01, no change

I have no idea if this is possible and if it is where to start from. Any help will be greatly appreciated.