Using various types in a 'using' statement (C#)

Other variable declarations in C# only allow you to declare multiple variables of the same type in the same statement; I don't see why using headers should be different.

You can do this though:

using (IDisposable cmd = new SqlCommand(), con = (cmd as SqlCommand).Connection)
{
   var command = (cmd as SqlCommand);
   var connection = (con as SqlConnection);
   //code
}

Perhaps that would be satisfactory to you.

There's no particularly good technical reason; we could have come up with a syntax that allowed multiple declarations of nonhomogeneous types. Given that we did not, and there already is a perfectly good, clear, understandable and fairly concise mechanism for declaring nested using blocks of different types, we're unlikely to add a new syntactic sugar just to save a few keystrokes.