Cannot open database “XXX” requested by the login. The login failed.

原来在数据库上的操作都很正常，可后来改了些代码，无缘无故地出现这个问题：

Cannot open database \"SmileCat\" requested by the login. The login failed.\r\nLogin failed for user ‘XXXXXX\\slin'

Solution:

http://stackoverflow.com/questions/454497/iis7-sql-2008-and-asp-net-mvc-security

Reference:

http://learn.iis.net/page.aspx/624/application-pool-identities/

现在在IIS7.5中已经可以按上面的解决方案解决了，可现在在VS中还是不行，遇到这样的错误：

{"Unable to open the physical file \"D:\\Shaowei\\Projects\\Src\\SmileCat\\Presentation\\SmileCat.WebApi\\App_Data\\SmileCat.mdf\". Operating system error 2: \"2(The system cannot find the file specified.)\".\r\nCannot open database \"SmileCat\" requested by the login. The login failed.\r\nLogin failed for user 'CXXXX\\slin'.\r\nFile activation failure. The physical file name \"D:\\Shaowei\\Projects\\Src\\SmileCat\\Presentation\\SmileCat.WebApi\\App_Data\\SmileCat.ldf\" may be incorrect."}