yyyy-mm-dd

Following Learning Zone videos, I decided in my genealogy database to use the ISO date format, because it has been suggested that the year, month and day have their own fields to facilitate sorting etc.

Often, the genealogy dates are not complete and only have a year or month for an event, birth, death.

I can to concatenate the yyyy-mm-dd, but when I only have a yyyy, how do I not have the hyphens in the string, so I only have yyyy.

Perhaps somebody can steer me on the correct path.