WordPress Database Design

Recently i have been working on WordPress plugin and related stuff a lot. There are times when i come across problems with the database of WordPress that required me to check or modify data in the table. However, i couldn't seems to find the correct source for the official WordPress database design which can really help understand a lot of the overall architecture practice of this open source application. But today i manage to find it and would like to share with people out there who can't find it because of various reason (Google fail you).