You could use an input mask to force it to upper case, but I guess a better
question is why are you building a login window?
There are certainly reasons to do so, but in almost all cases, the built-in
User-level security that ships with Access does a better job and is more
secure than any homegrown solution. If you do make a homegrown solution,
there are many important safety tips that you will want to follow. Can your
users simply open your table where the passwords are stored and read their
peers' passwords? Can they open the code behind your form and get around
it? Can they simply hold down SHIFT while opening the database and get
around your password completely? Can they open the data table directly and
edit the data without ever using your form?
Lots of things to consider. I almost always recommend using the tools that
come with access for securing your database. Unless you are pretty
advanced, you will most likely leave a few holes.
Good luck.
