Which books would you suggest for someone who wants to learn SQL on Oracle? Assume he has no idea about SQL and doesn't want to buy two separate books - one for SQL and other for Oracle.Also what are some cool websites for learning SQL on Oracle?
Take a look at the Oracle Database SQL Language Reference. Also, I have put together this page for Oracle related resources.
I've read a number of books on Oracle SQL and I've found Mastering Oracle SQL and SQL*Plus to be the best. A lot of books just cover the basics of how to write sql statements. They trim down and regurgitate Oracle's SQL Language Reference. This book starts off with the basic stuff but by the time you are done you have learned some advanced concepts and really understand the logic of how sql statements work. You can tell it was written by someone who is both a good teacher and really understands the topic. I found the exercises valuable too. If you work through these you'll have a decent intermediate level sql knowledge when you're done.
You may consider installing a local version of Oracle standard or enterprise to get you started. You can install the full blown version of oracle for free on a single machine for development only by a single user. (Please check the OTN T&Cs yourself)
However, a better start may be Oracle XE which allows you to learn and distribute for free. It's also aimed at the newer user so installation and maintenance is simpler.
For the Oracle Book consider printing the Oracle Concepts Guide. It provides a very good overview of the database. If you're in a hurry just read chapters 1, 4, 5, 13, 21, 22, & 24.
You can post your questions on http://www.oracleoverflow.com/, which is a dedicated Stack Exchange site for Oracle, run by Simple Talk Publishing.