Are you using MySQL 5.*? The BIT datatype, among other things, has changed since MySQL 4, and it looks to me as though the authors of DBD::mysql haven't had time to release an updated version. MySQL has a large number of changes & new features. If you are just messing around it doesn't matter, but if you are writing real code you have to consider whether you want to risk using a database version that isn't supported yet by the DBI. I wouldn't do it unless forced. Early adoption often leads to a lot of wasted time chasing incompatibilities between key software components as well as breakage due to brittle, non-road-tested new features.

New MySQL Features