SQL Reference link

SQL KEY TUTORIALS WEB SITES :

http://beginner-sql-tutorial.com/sql-index.htm

http://learnsqlwithbru.com/learn-sql-server/learn-sql-server-for-beginners/

http://www.w3schools.com/sql/default.asp

http://www.sqlcourse.com/intro.html

http://infogoal.com/sql/sql-basic.htm

http://www.katieandemil.com/sql-tutorial-for-beginners-with-examples-and-sql-tutorial-pdf

http://www.1keydata.com/sql/sql.html

http://www.java2s.com

http://www.tutorialspoint.com/

http://www.careerride.com/

SQL OTHER KEY WEB SITES: 

http://www.mssqltips.com/

http://blog.sqlauthority.com/

http://www.sqlquiz.com/

http://www.stevebin.net/Articles.aspx?Artld=QL08

http://sqlserver4us.blogspot.in/2012/07/what-are-different-types-of-triggers.html
http://www.codeproject.com/Articles/55505/SQL-Query-Optimization-FAQ-Part-1-With-video-expla
http://www.mssqltips.com/sqlservertip/2718/sql-server-index-column-order--does-it-matter/