Using Oracle and the SQL langauge are somewhat different things. Oracle has a lot of "features" like Oracle Forms and PL/SQL that are Oracle-specific.
Oracle comes with a learning "set" -- the scott/tiger schema. Most books that teach about Oracle and SQL assume you already have the "EMP" table for example.
The best book out there is "ORACLE Database 10g the Complete Reference" by Kevin Loney. (There is a ORACLE8 and an ORACLE9 version as well) If you are going to program in an Oracle environment you will have to get it sooner or later.
If you are just playing around with the free Oracle Express 10g then consider
"Oracle database 10g A Beginner's Guide" by Ian Abramson.
