MySQL 8.0

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create table patient (dateOfCheckup date, duration varchar(20))
insert into patient values('2020-05-28', '30 min');
insert into patient values('2020-05-29', '30 min');
insert into patient values('2020-05-30', '1 hour');
insert into patient values('2020-06-03', '1 hour 30 min');
insert into patient values('2020-06-05', '30 min');
insert into patient values('2020-07-21', '1 hour 30 min');
insert into patient values('2020-07-22', '30 min');
insert into patient values('2020-07-28', '1 hour 30 min');
select monthOfCheckup, dateOfCheckup, duration, minutes, total, case when sum(total >= 20) over (partition by monthOfCheckup order by dateOfCheckup) = 1 then 'Y' end 99457Elig,
case when sum(total >= 40) over (partition by monthOfCheckup order by dateOfCheckup) = 1 then 'Y' end 99458Elig
        from
(select
date_format(dateOfCheckup, '%Y-%m') monthOfCheckup,
dateOfCheckup,
duration,
((case when duration like '% hour%' then substring_index(duration, ' hour', 1) * 60 else 0 end) +
(case when duration like '%min%' then substring_index(substring_index(duration, ' min', 1), ' ', -1) + 0 else 0 end)) as minutes,
sum(((case when duration like '% hour%' then substring_index(duration, ' hour', 1) * 60 else 0 end) +
(case when duration like '%min%' then substring_index(substring_index(duration, ' min', 1), ' ', -1) + 0 else 0 end))) over (partition by date_format(dateOfCheckup, '%Y-%m') order by dateOfCheckup) total
 from patient) as a;


monthOfCheckup
dateOfCheckup
duration
minutes
total
99457Elig
99458Elig


2020-05
2020-05-28
30 min
30
30
Y
null

2020-05
2020-05-29
30 min
30
60
null
Y

2020-05
2020-05-30
1 hour
60
120
null
null

2020-06
2020-06-03
1 hour 30 min
90
90
Y
Y

2020-06
2020-06-05
30 min
30
120
null
null

2020-07
2020-07-21
1 hour 30 min
90
90
Y
Y

2020-07
2020-07-22
30 min
30
120
null
null

2020-07
2020-07-28
1 hour 30 min
90
210
null
null

monthOfCheckup	dateOfCheckup	duration	minutes	total	99457Elig	99458Elig
2020-05	2020-05-28	30 min	30	30	Y	null
2020-05	2020-05-29	30 min	30	60	null	Y
2020-05	2020-05-30	1 hour	60	120	null	null
2020-06	2020-06-03	1 hour 30 min	90	90	Y	Y
2020-06	2020-06-05	30 min	30	120	null	null
2020-07	2020-07-21	1 hour 30 min	90	90	Y	Y
2020-07	2020-07-22	30 min	30	120	null	null
2020-07	2020-07-28	1 hour 30 min	90	210	null	null