I work for an elephant that creates, manages, supports other elephant software needs including Microsoft and Sun, no I don't think Oracle is included.  Here is what we do, the application main database runs on Oracle, and reports runs on SQL Server or both runs on SQL Server. The customer makes the call, the suits meets with the customer every week or month as needed.  My current project both ends run on SQL Server.  In Oracle we don't use PL/SQL but in SQL Server we use T-SQL, the teams using Oracle and SQL Server use Vault source control, the SQL Server team uses VSS.  Yes you can write portable code but you have to plan and pay for skilled data people and give some money to your friends at Data Direct the people who sells the XQUERY tool, they also sell socket level drivers that can help you write portable code.  The questions is will your customer pay for it the answer from most elephants no.