So, in going around the room at mysqlcamp this morning, only one person mentioned having using another database (SQL Server & Sybase). Another mentioned Access…..but that’s not a “real” database.
But many people mentioned connections to Oracle — be it “used to work for Oracle” or “used to use Oracle”. I think this speaks to how similar Oracle and MySQL are. Now, there are PLENTY of differences. But compared to Sybase, Microsoft SQL Server, Ingres, Postgres and IBM DB2, it sounds like MySQL and Oracle are closer to each other than MySQL and any other database.