This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
In most cases a DB comes with its own driver, which is then kind of the default choice. That's certainly the case for all major DBs (SQLServer, DB2, Oracle, Informix, Sybase, PostgreSQL, MySQL). So in practice, it's not like you have a choice anyway. (The only DB I'm aware of that has multiple drivers available is SQLServer, and even there you'd generally go with Microsoft's driver.)