Back when I was doing a lot of database work, I was annoyed that open source databases (mysql, postgres, firebird) were all the rage, but there were so few open viewers/managers, much less portable ones. PortableApps offered a query tool/viewer
a while back that worked pretty well, but not an open one. Fortunately there are now two available from PortableApps, including one that allows some database creation that would work as an amazing "intro to databases" tool:
Anyway, I haven't tested these out extensively, but I'm glad to see moves in this realm.