- SQL TUTORIAL
http://www.ilook.fsnet.co.uk/ora_sql/sqlmain.htm 

ORACLE 9i SQL REFERENCE
http://www.lc.leidenuniv.nl/awcourse/oracle/server.920/a96540/toc.htm - 

A Gentle Introduction to  SQL
http://sqlzoo.net/

http://lepo.it.da.ut.ee./~askot/oracle9idba/