Depends.
If you did it on your own time it may be yours.
If on company time it's almost certainly theirs.
You will need to speak with an attorney to
find out what is most likely.
Good advice. There are "defaults" but there are so many things that can
affect it, that you really need advice from a qualified attorney,
preferrably one who specializes in copyright, patent, and intellectual
property law in the jurisdiction in which you reside, or in which the work
was done.
There are newsgroups, I am sure, where such issues are discussed. This is
not one of them... it is devote to techical questions and answers about
Microsoft Access database software.
Larry Linson
Microsoft Access MVP