Sql>select file#,name,status,enabled from v$datafile;
在线的状态为：
NAME
--------------------------------------------------------------------------------
STATUS ENABLED
------- ----------
/u01/metadata/ts0002.dbf
ONLINE READ WRITE
7
/u01/metadata/ts0003.dbf
ONLINE READ WRITE
离线的状态为:
/optnew/oracle/oradata/orcl/user10.dbf
RECOVER READ WRITE
18
/optnew/oracle/oradata/orcl/user11.dbf
RECOVER READ WRITE
19
/optnew/oracle/oradata/orcl/users12.dbf
RECOVER READ WRITE
alter database datafile 3 online;
alter database open;