I want to learn pl/sql

yes definately my friend go to java2s website its complete guide to plsql & sql,with all theories & all type of examples!

On the website of otn, there are tons of material about database http://otn.oracle.com/ If you want to be VERY good at pl/sql, please also try to learing the oracle concept, such as the oracle objects, iosolation level(which is far different from sql server, db2...), and oarcle architecture(this is very important to write best performace sql). Another good website for you is asktom.oracle.com. I work as an oracle dba for HP and find that asktom.oracle.com teach me more than other site except otn.oracle.com