SQL

Good Learning Site for beginners:
Short:
http://www.dofactory.com/sql/left-outer-join

Elaborate:
https://www.w3schools.com/sql/sql_select.asp

Less Important But Okay:
https://www.tutorialspoint.com/sql/index.htm
Questions:

http://programabad.com/questions/5268/sql-normalization

http://www.studytonight.com/dbms/database-normalization.php

http://programabad.com/questions/3940/cgpa