Check username in Single user Mode

use master

GO

select

    d.name,

    d.dbid,

    spid,

    login_time,

    nt_domain,

    nt_username,

    loginame

from sysprocesses p

    inner join sysdatabases d

        on p.dbid = d.dbid

where d.name = 'dbname'

GO

kill 56 => kill the number in spid field

GO

exec sp_dboption 'dbname', 'single user', 'FALSE'

GO

USE master

GO

DECLARE @kill varchar(8000) = '';

SELECT @kill = @kill + 'kill ' + CONVERT(varchar(5), spid) + ';'

FROM master..sysprocesses

WHERE dbid = db_id('dbname')

EXEC(@kill);

USE [master]

SET DEADLOCK_PRIORITY HIGH

exec sp_dboption '[dbname]', 'single user', 'FALSE';

ALTER DATABASE [dbname] SET MULTI_USER WITH NO_WAIT

ALTER DATABASE [dbname] SET MULTI_USER WITH ROLLBACK IMMEDIATE