You've got a long way to go. I did the other way round a couple of months back and was able to move in properly but still insisted on doing the courses as syntax maybe a bit different but the databases are huge beasts who behave differently.
Startup by reading the concepts manual, it's, IMHO very crucial that you read this manual at least thrice. Architectural understanding is crucial in understanding databases.
Oracle doco's are for free so you can download them in pdf format's as well.
If you want to be doing a serious oracle dba you'll have the...
2. perf tuning manual
3. backup, reco and rman manual.
4. admin guide
...pdf's printed, bounded on your desk at all times.
Here the concept's manual to start with ...http://download-west.oracle.com/docs...a96524/toc.htm
and this the link to read/download all manuals...http://download-west.oracle.com/docs...v/docindex.htm
Welcome to the real database
Hope that helped...
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