SQL优化

http://blog.csdn.net/it_man/article/details/6602142

http://www.cnblogs.com/sishahu/archive/2012/02/16/2353714.html

http://topic.csdn.net/u/20100415/10/a377d835-acbd-4815-8bcb-b367f88ac8b5.html?92227

http://blog.csdn.net/tianlesoftware/article/details/7008801

http://caowenkun.iteye.com/blog/1114534