dBforums - Restoring database from mdf and ldf: "Have you read how many posts we have in these newsgroups that have problems attaching databases that
weren't detached first? Just because it might have worked for you doesn't mean it is supported or
that it always work!

Here is a very important quote from Books Online:

'sp_attach_db should only be executed on databases that were previously detached from the database
server using an explicit sp_detach_db operation. '

Do you still consider planning a backup strategy based on just copying the database files and hoping
that they will attach successfully a good idea?"