Suggest One comprehensive book on sql and one on pl/sql

Hi all,
Please Suggest One comprehensive book on sql and one on pl/sql. I have searched it on net and got a lot of books but baffled by the different names doing the rounds.
Can anyone please tell me from experience which book is good for beginners and advanced programmers and which has a lot of example programs.

Or if there is a good ebook available.
Any suggestion is welcome.

thanks

Did you try Oracle's own documentation already? It is freely available to anybody, and probably as comprehensive as it gets..

I'd suggest starting with the Concepts to get rough ideas about how Oracle works and what can be done with it, and then continuing with SQL Language Reference and PL/SQL Language Reference. All of these can be found here for 11.1, but look up the version matching the database you are working with.