MySQL 8.0

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create table dates (
year int, 
month varchar(2), 
day int, 
hour int, 
minute int, 
date_time timestamp
);
insert into dates (year, month, day, hour, minute) values
(1987, '12', 15, 9, 25),
(1997, '10', 10, 10, 40),
(1994, '08', 9, 6, 30);
UPDATE dates
SET date_time = CONCAT(DATE(year*10000 + month*100 + day),' ',MAKETIME(hour,minute,0));
select * from dates


year
month
day
hour
minute
date_time


1987
12
15
9
25
1987-12-15 09:25:00

1997
10
10
10
40
1997-10-10 10:40:00

1994
08
9
6
30
1994-08-09 06:30:00

year	month	day	hour	minute	date_time
1987	12	15	9	25	1987-12-15 09:25:00
1997	10	10	10	40	1997-10-10 10:40:00
1994	08	9	6	30	1994-08-09 06:30:00