These are some awesome site on database.
http://www.esp.org/db-fund.pdf [2]
http://wserver.flc.losrios.edu/~davis/Chapter1.htm [3]
http://www.tutorialspoint.com/sql/sql-rdbms-concepts.htm [4]
http://en.wikibooks.org/wiki/Relational_Database_Design/Basic_Concepts [5]
http://dbmsbasics.blogspot.in/ [6]
Links
[1] https://hootsgo.org/?q=content/basic-concepts-1
[2] http://www.esp.org/db-fund.pdf
[3] http://wserver.flc.losrios.edu/~davis/Chapter1.htm
[4] http://www.tutorialspoint.com/sql/sql-rdbms-concepts.htm
[5] http://en.wikibooks.org/wiki/Relational_Database_Design/Basic_Concepts
[6] http://dbmsbasics.blogspot.in/
[7] http://www.cs.umb.edu/cs630/hd1.pdf