How to indicate the date in the file with climate information?

Question

Data types

I am working with a climate database, I ran into such a task, the date is basically indicated as 19360101
, that is, 1936 on January 1st. So it is convenient to name the files, because then it is convenient to sort them in order. But! each time you have to write the date, is it possible to create such a data type (maybe) so that from the first 4 digits (year) they go in order, the next 2 digits change from 1 to 12 (month) and the last two digits change from 1 to 30, 28 or 31, depending on the month? maybe there is another solution?