离线：
ALTER DATABASE <dbname> SET OFFLINE WITH ROLLBACK IMMEDIATE
ALTER
DATABASE
<dbname>
SET
OFFLINE
WITH
ROLLBACK
IMMEDIATE
在线：
ALTER DATABASE <dbname> SET online WITH ROLLBACK IMMEDIATE
数据库离线、在线
原文：https://www.cnblogs.com/liujianshe1990-/p/11521489.html
