我需要重新启动数据库，因为某些进程无法运行.我的计划是离线，然后重新上线.
我正在Sql Server Management Studio 2008中try 这样做:
use master;
go
alter database qcvalues
set single_user
with rollback immediate;
alter database qcvalues
set multi_user;
go
我发现了以下错误:
Msg 5061, Level 16, State 1, Line 1
ALTER DATABASE failed because a lock could not be placed on database 'qcvalues'. Try again later.
Msg 5069, Level 16, State 1, Line 1
ALTER DATABASE statement failed.
Msg 5061, Level 16, State 1, Line 4
ALTER DATABASE failed because a lock could not be placed on database 'qcvalues'. Try again later.
Msg 5069, Level 16, State 1, Line 4
ALTER DATABASE statement failed.
我做错了什么？