在oracle open方式下，直接从OS上删除了datafile文件。
1、在Oracle open方式下，直接从OS上删除了datafile文件。
rm /u02/rmants.dbf
2、数据库关闭后，无法打开数据库，，只能到mount状态。
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01157: cannot identify/lock data file 7 - see DBWR trace file
ORA-01110: data file 7: '/u02/rmants.dbf'
3、在mount状态下，删除被误的数据文件。
alter database datafile '/u02/rmants.dbf' offline drop;
4、打开数据库
alter database open;
5、验证状态
select open_mode from v$database
OPEN_MODE
--------------------
READ WRITE
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