SQL stands for Structured Query Language. It’s a standard language for accessing and manipulating databases. MySQL is a database management system, like SQL Server, Oracle, Informix, Postgres, etc.
Oracle is determined to keep MySQL if it acquires Sun, but the reason likely has little to do with open source and everything to do with Microsoft. Oracle doesn't compete with open source. Not really.
OK, while I'm really bad about approving comments (mostly because the platform makes it so painful), I do want to answer a few of them here real quick. First and foremost because this is bothering me.