Find material for improvement of my SQL ability
If you are looking to just improve your SQL coding ability I would go to the following sites:


http://www.sqlservercentral.com - check out the scripts section
http://www.sqlcourse.com/index.html - this site has some good basic tutorials
http://www.sql-tutorial.net/ - also another good site for tutorials
http://www.mssqltips.com/ - covers a lot of different areas but still has good material
http://blog.sqlauthority.com/ - VERY knowledgeable fella. Just search his site for what you are looking for


Here is a list of sample SQL databases for you - http://msftdbprodsamples.codeplex.com/

For some FREE reading on check out - http://www.sqlservercentral.com/articles/books/67441/