EXECUTE Northwind.dbo.sp_who should have worked and printed Surprise.

Actually not, it has something to do with the name resolution, but any procedure that starts sp_ is first looked for in master, no matter if it's fully qualified or not. I tried that just now.

USE

Northwind

GO

CREATE

PROCEDURE sp_who

AS

PRINT 'Surprise'

GO

EXEC

sp_who

EXEC Northwind.dbo.sp_who

and in both cases I got the process list back.

I do recall playing with this some time back, and if the user-created stored proc is owned by someone other than dbo, then it can be executed with a fully qualified name. If it's owed by dbo then the one in master is always run, no matter how qualified the call is.