Brute force database out of SINGLE_USER mode back into MULTI_USER mode

Query window 1.sql

-- run this in query window 1:

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
SET DEADLOCK_PRIORITY HIGH;
GO
DECLARE @CMD nvarchar(max) = ''
SELECT @CMD = CONCAT(@CMD, CHAR(10), 'KILL ', session_id)
FROM sys.dm_exec_requests
WHERE database_id = DB_ID('MyDB') -- replace MyDB with your DB name

PRINT @CMD
EXEC (@CMD);
GO
-- replace MyDB with your DB name:
USE MyDB
ALTER DATABASE MyDB SET MULTI_USER;

Query window 2.sql

-- run this in query window 2:

DECLARE @CMD nvarchar(max);

WHILE 1=1
BEGIN
	SET @CMD = NULL;
	SELECT @CMD = ISNULL(@CMD + CHAR(10), '')
			 + CONCAT(N'KILL ', blocking_session_id)
	FROM sys.dm_exec_requests
	WHERE session_id = 1234 -- replace with the session id of query window 1

	IF @CMD IS NULL BREAK;
	RAISERROR(N'%s',0,1,@CMD) WITH NOWAIT;
	IF @CMD <> 'KILL 0' EXEC(@CMD);
END