MySQL User and DB Tables

[Jonathon Wright]

Hello,

I am running MySQL Server 5.1.71 on FreeBSD 64Bit platform that was setup by another DBA originally and I'm now the DBA. Today I noticed that there are entries in the mysql.user table that do not have entries in the mysql.db table.

I've read up on the Reference guides:
http://dev.mysql.com/doc/refman/5.1/en/default-privileges.html
http://dev.mysql.com/doc/refman/5.1/en/adding-users.html

but not quite sure why there would be a need to have accounts in the user table with no entries in the db table. As far as I know, this would mean the user can log in, but has no permissions to any database. If that is true, what would be the use of those accounts?

To make it more odd, I do know that one of the accounts is being used to run queries against a db (via php scripts), but how is that possible if there is no entry in the db table? Or did I miss something...

Thanks for the help!