declare @dbname sysname, @spid int, @cnt int, @sql varchar(2048)

set @dbname = 'targetDB'

select @spid = min(spid), @cnt = count(*)
from master.dbo.sysprocesses
where dbid = db_id(@dbname) and spid != @@spid

print @dbname + ' connection process(es) to kill: ' + rtrim(@cnt) 

while @spid is not null
begin
print 'kill connection process ' + rtrim(@spid)
set @sql = 'kill ' + rtrim(@spid)
exec(@sql)
select @spid = min(spid), @cnt = count(*)
from master.dbo.sysprocesses
where dbid = db_id(@dbname)
and spid != @@spid  
end

print 'done'

use master
alter database [db_name] set offline with rollback immediate