1. You can not use RED HAT, the closest thing was http://pidora.ca but that's dated so it's recommended you use Raspbian Jessie Lite which is close to Debian (and ubuntu/mint/etc). Other options 2. Oracle is not likely to have a build for the pi but postgresql and mysql are better anyway. 3. You can...
1) Title your posts properly.
2) There is no need to buy a raspberrypi to learn programming any computer will do.
3) The raspberrypi is about to become obsolete the same way any computer is, the main difference is the raspberrypi is $5 to $100, and normal computers are $70 to $5k.