Use single connection string in Project & Class Library in same Solution

I used while using LINQ to SQL classes and wanted to have only one connection string in the project's web.config and no other connection string in app.config of the DAL class library project

http://fuchangmiao.blogspot.com/2008/11/linq-appconfig-vs-webconfig.html

http://ddkonline.blogspot.com/2008/02/set-connection-string-in-linq-dbml-file.html

http://blogs.msdn.com/jongallant/archive/2007/11/25/linq-and-web-application-connection-strings.aspx

http://stackoverflow.com/questions/450598/change-connection-string-from-class-library-in-main-application-at-run-time

http://geekswithblogs.net/vivek/archive/2007/02/24/107209.aspx