如何从asp.net网站管理数据库访问的密码

Just curious as to best practice for managing db access from an asp.net web application. We were currently putting the username and password in the web.config, but this wasn't good enough internal security (obviously), so I decided to use a windows domain user instead by modifying the web.config to use windows domain, and then adding the user to the app pool identity. This all works fine, but what happens when the domain user's password changes? Does that mean that all the webapps that use this user's identity in app pool will require the password change too? This would be an IT nightmare. Does anyone have suggestions on best approach for allowing webapp to access database without exposing password and without having to update passwords in all webapps if the password changes? ThanksJust curious as to best practice for managing d