Query Help. This Works, But I Don't Think It Is Good Practice

comics:
id
date
location

comments:
id
comicid
datetime
header
comment
author

Every comic can have multiple comments. Each comic will have a comment, but there is a period of time where the comic is posted but the first comment is not yet submitted. So for argument's sake we can't assume there is any comment at all for a given comic.

I want the all the comic ids and dates before a certain date along with the most first comment entered relating to that comic.

select comics.date
, comics.id
, comments.header
from comics
left outer
join comments
on comments.comicid = comics.id
where (comics.date>=񟭇-03-01')
group by comics.id
I never defined WHICH header should be returned when many are grouped together. I just know that mysql will return the first one in this circumstance. I seem to recall reading somewhere that different databases handle this sort of thing differently, with some returning a null in that field?

I keep trying to forumate a useful subquery but keep drawing blanks just as I think I have it figured out in my head. Like I forget how the string starts by the time I mentally formulate the end....