I have a team of three developers, two of whom use a standard local test database, one of whom uses his own database and there is also a server environment with a production database and a testing database.
This amounts to multiple connection strings required.
The web.config file periodically gets updated and keeps having to be changed by each developer when a source control update is performed, as well as the fact that sometimes a developer accidentally checks in his personal web.config file change with his connection string, which temporarily interrupts us after running a subsequent update from source control.
What can I change so that the web.config file can be committed/updated as often as is necessary and not result in broken connection strings for other developers or require modifications before it can be uploaded to the testing or production environments?
You might want to look at replacing the ConnectionStrings section of the Web.Config with a Config Source file, commit the LIVE set of connection strings into source control, but not include them in the actual solution.
Information on using the configSource attribute can be found in the section "Using External Configuration Files" in the document:
This has the advantage that developers could have their own settings that don't get checked into the main Web.Config. The potential downside is that it's yet another file that you have to worry about, and depending on how you're getting the latest version out of source control might not help (i.e. if you go to your SC client and say "Get latest" that would overwrite the file, whereas if you are in Visual Studio, right click on the solution/project and select "Get Latest" that will only get files in the projects).
For the question regarding the testing and production environments, you can make use of the Visual Studio Web Deployment Projects. With that, you can define sections in the web.config that will be replaced when you build the deployment package for the test / prod server.
You could use the Enterprise Library Data Access Block to handle your database connections. You can then define as many connection strings as you want and simply change the use key to whichever one is required. See http://www.devx.com/dotnet/Article/30910 for more information.
来源：https://stackoverflow.com/questions/1221708/asp-net-configuration-file-connection-strings-for-multiple-developers-and-dep