SQL Server – Should dbo Be Dropped from Database Role db_owner

Each database is owned by a server principal (aka login). Inside that database, the owning principal is known as dbo (aka *D*ata*B*ase *O*wner). The database principal (aka user) loses its real name.

For example, for a database I own:

select  [user].name as UserName -- Database specific
,       [login].name as LoginName -- Server wide
from    sys.databases d
join    sys.database_principals as [user]
on      [user].sid = d.owner_sid
join    sys.server_principals as [login]
on      [login].sid = d.owner_sid

Will print "dbo", "Andomar". If you'd change the owner to sa:

exec sp_changedbowner 'sa'

The query would return "dbo", "sa".

You cannot modify the default schema for the user that owns a database. It is always user name dbo with default schema name dbo.

I can guess you have the AutoClose option for database set to True. This is the default behavior when you create a database with Express Editions.

The mentioned error can occur exactly in this case. Actually the complete error message 615 states: "Could not find database ID %d, name '%.*ls'. The database may be offline. Wait a few minutes and try again." ... So it points that database could be closed during dropping.

So, go to DB properties, switch it to False and try again dropping it or use below script before dropping

ALTER DATABASE [MyDB] SET AUTO_CLOSE OFF 
GO

Many point out that is better to have AutoClose set to False. I found this article explaining a bit more about AutoClose: http://sqlmag.com/blog/worst-practice-allowing-autoclose-sql-server-databases

Small extension of the answer:

-- this works in standard SQL Server Editions, but NOT with Express Editions:
CREATE DATABASE [MyDB]
GO
DROP DATABASE [MyDB]
GO

-- this works in ALL SQL Server Editions
CREATE DATABASE [MyDB]
GO
ALTER DATABASE [MyDB] SET AUTO_CLOSE OFF 
GO
DROP DATABASE [MyDB]
GO