Fix that db_owner's login name is sa

Use sp_helpuser to view the recovered database.
> Username groupname loginname defdbname userid Sid
> ---------------------------------------------------
> DBO db_owner null 1 0x01

The first time I saw this situation, fortunately, the following SQL statement can fix that the login name of db_owner is Sa.
Exec sp_configure 'Allow updates', '1'
Go
Reconfigure with override
Go

Update sysusers
Set SID = (select Sid from Master .. syslogins where loginname = 'sa '), updatedate = getdate (), status = (Status &~ 1) | 2
Where name = 'dbo'

Exec sp_configure 'Allow updates', '0'
Go
Reconfigure with override
Go