Kill SQL Server database connections

USE master
go

DECLARE @dbname sysname
SET @dbname = 'yourdbname'

DECLARE @spid int
SELECT @spid = min(spid)
 from master.dbo.sysprocesses
 where dbid = db_id(@dbname)

WHILE @spid IS NOT NULL
BEGIN
EXECUTE ('KILL ' + @spid)
SELECT @spid = min(spid)
FROM master.dbo.sysprocesses
WHERE dbid = db_id(@dbname)
 AND spid > @spid
END