How you restore the file depends on the backup methodology you used. If you do not have a backup, then your entire database is lost. If you are not running in Archive log mode, then you'll have to shut down the database and restore all of the datatabase files from your backup, then start your database. You will have lost all transactions since your last backup.
If you are running in Archive log mode, then shut down your database, restore just the SYSTEM tablespace's datafile, then do START MOUNT in SQL*Plus. Issue RECOVER DATABASE followed by ALTER DATABASE OPEN, and you are ready to go.
If your backup was performed with RMAN, then let RMAN perform the recovery. RMAN will make all of the decisions for you and perform the requisite actions.
Dig Deeper on Oracle database backup and recovery
Related Q&A from Brian Peasland
Oracle expert Brian Peasland answers one reader's question about common pitfalls when connecting Oracle to outside programs. Continue Reading
One reader asks expert Brian Peasland a question about datafile sizes with the Oracle RMAN duplicate 10g command. Continue Reading
Managing parent table-child table relations in Oracle SQL environments is key to efficient programming. Continue Reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.