Declare @datadir nvarchar(4000)

,@logdir nvarchar(4000)

,@backupdir nvarchar(4000);

EXEC master.dbo.xp_instance_regread

N'HKEY_LOCAL_MACHINE'

, N'Software\Microsoft\MSSQLServer\MSSQLServer'

, N'DefaultData'

, @datadir output;

IF @datadir IS NULL

BEGIN

EXEC master.dbo.xp_instance_regread

N'HKEY_LOCAL_MACHINE'

, N'Software\Microsoft\MSSQLServer\Setup'

, N'SQLDataRoot'

, @datadir output;

END

EXEC master.dbo.xp_instance_regread

N'HKEY_LOCAL_MACHINE'

, N'Software\Microsoft\MSSQLServer\MSSQLServer'

, N'DefaultLog'

, @logdir output;

EXEC master.dbo.xp_instance_regread

N'HKEY_LOCAL_MACHINE'

, N'Software\Microsoft\MSSQLServer\MSSQLServer'

, N'BackupDirectory'

, @backupdir output;

SELECT @datadir as Data_directory, ISNULL(@logdir,@datadir) as Log_directory, @backupdir as Backup_directory;