Question about how to learn ABAP programming

Dearl all

I am supporting internal SAP users in my company, and I am going to do a bit of programming in ABAP language from now on.

I have learned a basic ABAP programming with the book below.

<Book>

ABAP Objects: Introduction to Programming SAP Applications [Hardcover] --> Horst Keller

However, I want to know more about the following topics.

1. How to creat efficient programs (ex. using work area, using select statement efficiently, etc)

2. How to improve the performance of the programs (=performance tuning, how to measure the performance, etc)

3. How to create/modify user exits

Could you tell me books or tutorial sites where I can get more knowledge on those topics?

(I'm looking for something which is not too theoretical ones as I am not a very experienced programmer...)

Thank you very much in advance.

Takashi

Moderator message : Moved from "ABAP General" to "Career Center".

Edited by: Vinod Kumar on Nov 14, 2011 10:33 AM