Links to learn PL/SQL and Oracle SQL:
http://safari.oreilly.com/?XmlId=0-596-00381-1
http://www.orafaq.com/faqplus.htm
http://www.ss64.com/ora/
http://www.redhat.com/docs/manuals/database/RHDB-2.1-Manual/sql/sqlreference.html
http://www.psoug.org/reference/forms.html
http://www.mckoi.com/database/SQLSyntax.html
http://www.orafaq.com/faq/
http://www.ilook.fsnet.co.uk/ora_sql/sqlmain.htm
http://www.w3schools.com/sql/
http://www.vbip.com/books/1861001789/chapter_1789_02.asp
http://www.unix.org.ua/orelly/oracle/prog2/index.htm
http://www.unix.org.ua/orelly/oracle/
http://docs.hp.com/en/36216-90216/index.html
http://dnaugler.cs.semo.edu/oracledocs/a90842/
http://sqlcourse.com/select.html
http://members.tripod.com/er4ebus/sql/ch20.htm
http://www.cs.umbc.edu/help/oracle8/server.815/a67779/function.htm#1026778
SQL Loader:
http://www.oreilly.com/catalog/orsqlloader/chapter/ch01.html#92106
I guess learning sql without a database to practice it on isn't very instructive.
why don't you learn about databases first.
I suggest mysql server. But even postgresql is great.
Then get a generic sql book e.g. www.quantrimang.com/download/ebooks/(ebook%20pdf)%20Teach%20Yourself%20SQL%20in%2021%20Days.pdf
and start learning sql that works on any dbms(Database management system e.g postgresql , oracle ) before tackling the specificities of each.