Can anybody tell me if there is a function which checks uniqueness of a username across ALL portals?  What I want to achieve is to make sure a username doesn't exist before I create a user account. It seems to me user creation will fail even the username exists in other portals.

Thanks in advance.

Hi Frank,

If you happen to be using AspNetSqlMembershipProvider and won't be migrating away from this provider in the future, you could use this functionality to determine username uniqueness.  This provider includes a clustered, unique index over ApplicationId and the lower-case username.  Since DNN only uses one ApplicationId across ALL portals ("DotNetNuke"), you can safely use the ASP.NET provider-based GetUserByName (not the DNN membership provider though!) to query username existance.

Obviously, other provider implementations may handle username uniqueness differently, so switching providers might result in a change in behavior.

Hope this helps!

Brandon