Ok, if you're going to use mySQL, then choose php (well, you could use C#, but it would be harder because your server has to support asp.net) Now then, if you're going to use MS SQL, then by far choose C# (asp.net). Just make sure you server suppors asp.net.
If you end up using asp.net and ms sql, it should only take you a few days to write the program, it's not hard at all.