You can use a recursive CTE to generate all the days of a month:

with recursive march_days as
(select convert('2022-03-01', date) as d
union all 
select date_add(d, interval 1 day)
from march_days
where d < '2022-03-31')
select * from march_days;

Fiddle

Hello and welcome to Stackoverflow.

In php you can get the days with a for loop.

for($i=1; $i<=31; $i++) {
    # Do your date things here.
}

That is just a basic counter, without more to go on from your project, code sample etc, then it is unlikely that we will be unable to give you better direction on this.