Drop Tablespace With Datafile Missing

1. shutdown database.
2. startup database in mount status.
3. alter database datafile ‘PATH/filename’ offline drop.
4. open database.
5. drop tablespace tablespace_name including contents.

Note, the following errors could be seen in alert.log:

ORA-01135: file 4 accessed for DML/query is offline
ORA-01110: data file 4: ''

ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4: ''
ORA-27037: unable to obtain file status
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3