I'm struggling to think how a checksum for an entire database could be generated. Databases usually use checksums for their smallest data usings (e.g. a page in SQL server or a data block in Oracle), generating one for an entire database is not something I've ever heard of (though that's not to say it isn't done). I'm also struggling to think how a table or database checksum could be any use. There are so many differentials in a relational database table the chances of getting two identical checksums from two different tables must be a possibility surely?