rdbms

http://webcast.idready.org/materials/spr07/relational_database/2006-12-01/RDBMS.ERDiagrams.pdf

http://en.wikipedia.org/wiki/Entity-relationship_model

http://distancelearning.ksi.edu/demo/331/cis331.htm

http://www.techbirbal.com/viewtopic.php?f=91&t=912

http://codex.cs.yale.edu/avi/db-book/slide-dir/index.html

http://www.db-book.com/