MDF is the format that Microsoft Access uses. You can set up an ODBC connection, or with Visual Studio I think there’s a way to establish a connection via some GUI options. As for actual code, I haven’t touched .NET in ages, so I have no idea Smile
The best database is a tricky question, because that depends on scalability, cost, timelines, etc. For a simple setup, try a real database like MySQL or PostgreSQL.
MDF is not Access, it is MS SQL server database. (Master Data File)
When you create a database in MSSQL Server it will create one MDF file and one LDF file, the LDF is a log file.
when you create a database with SQL Server Express, the MDF File will be added to your ASP.Net application.
When you start working with ASP.Net, the best choice in DB Server is a SQL Server database. You can use MSSQL Express, or Compact databases.
Advantage is that you can use Entity Framework and that is in my opinion the fastest way to set up a database and a good way to use that database, especially for a beginner.
Use the ADO.NET EntityFramework to make your life a lot easier.
Anyway, if you’re going to make something that involves multiple users and multiple queries being executed on the database at any given time, don’t use Access or you’ll run into concurrency issues sooner or later. Obviously MSSQL works best with .NET, as they’re both Microsoft technologies and they tend to give that little bit of extra compatibility with their own products. However, MySQL or any other ODBC database should work just fine.