How do I get the UserId from aspnet_Users after CreateUser() to use as a foreign key in another Table?

I've been following a tutorial on www.asp.net and the username doen't have to be unique. Is there any other way of doing it or do you think it'd best to make unique usernames a requirement?

Thanks

I'm quite happy to set it so that a new member requires a unique user name but how do I do that?

When catching a 'MembershipCreateUserException' one of the cases for an error message is as follows...

case MembershipCreateStatus.DuplicateUserName: return "There already exists a user with this username.";

This implies I can set the membership provider to only allow unique usernames. But all I can see in the Web.Config provider settings is...

requiresUniqueEmail="true"

but no requiresUniqueUserName option.

My mistake... somehow I have created to users with the same name but now it won't let me.

I can now user the Username in:

Membership.GetUser("username").ProviderUserKey.ToString();

And it works!

Thanks