oracle 启动时出现ORA-01157: cannot identify/lock data和ORA-01110: data file 错误

SQL> shutdown
ORA-01109: database not open
Database dismounted.

ORACLE instance shut down.

SQL> startup
ORACLE instance started.
Total System Global Area  422670336 bytes
Fixed Size    1336960 bytes
Variable Size  314575232 bytes
Database Buffers  100663296 bytes
Redo Buffers    6094848 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 6 - see DBWR trace file
ORA-01110: data file 6: '/bk/dba_tablespaces/ts3.dbf'

SQL> alter database open
  2  ;
alter database open
*
ERROR at line 1:
ORA-01157: cannot identify/lock data file 6 - see DBWR trace file
ORA-01110: data file 6: '/bk/dba_tablespaces/ts3.dbf'

SQL> alter database datafile '/bk/dba_tablespaces/ts3.dbf' offline drop;
Database altered.

SQL> alter database open
  2  ;
alter database open
*
ERROR at line 1:
ORA-01157: cannot identify/lock data file 9 - see DBWR trace file
ORA-01110: data file 9: '/bk/dba_tablespaces/ts6.dbf'

SQL> alter database datafile '/bk/dba_tablespaces/ts6.dbf' offline drop;
Database altered.

SQL> alter database open
  2  ;
Database altered.