drop tablespace when datafiles accidentally deleted

1. Run SQL*Plus.
2. Connect to database as SYSDBA with this query:

   CONNECT / AS SYSDBA

3. Mount the database instead of starting it up:

   STARTUP MOUNT;

4. Issue the following command to bring the missing datafile offline so that Oracle won’t trying to connect and access the datafile anymore:

   ALTER DATABASE DATAFILE ‘’ OFFLINE DROP;

   Repeat the command for every datafiles that unaccounted for.

5. Now start the database proper:

   ALTER DATABASE OPEN;

6. As the tablespace has damaged, drop it to recreate from fresh backup.

   DROP TABLESPACE INCLUDING CONTENTS;