MysqlDialect incorrectly maps java.lang.Boolean to SQL BIT ---------------------------------------------------------- Key: HHH-468 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-468 Project: Hibernate Core Issue Type: Bug Affects Versions: 3.0.3 Environment: Hibernate 3.0, MySQL. Reporter: Mark Matthews Assignee: Steve Ebersole Fix For: 4.0.0.Alpha2 I didn't track down how java.lang.Boolean gets mapped to Types.BIT in hibernate, but you probably _don't_ want to map to "bit" like you do in MysqlDialect. "bit", according to SQL99 (it's not in the core standard, and the type was actually dropped for sql2k3) is a bitfield, not a boolean value. You can of course define a bit(1), but it is technically more correct for java.lang.Boolean to map to a SQL BOOLEAN for MySQL since we support a BOOLEAN and a BIT. It looks like the JDBC-3.0 guys ignored what the standard said, because in reality you'd want BIT to map to something like byte[], or java.util.BitSet if you were tracking how the SQL standard defines BIT. I'm guessing you probably want to map to "boolean", which the JDBC driver will automagically convert for you, as it silently maps to TINYINT(1) on the server side.