How do you limit the length of text the user enteres into a row in a dbgrid?

The problem I'm having is that the particular field that a column in the dbgrid is attached to in my database has a length of 50. If the user enteres more than that in the dbgrid, is just says "Errors Occured". What I want to do is simply prevent the user from entering more than 50 characters so that when the user hits 50, it simply does not allow him to type any more characters..

Any help would be appreciated..

dan