Oracle has introduced flashback technology to restore database object states from the past. It can also retrieve inadvertent modifications that were committed. The value of the UNDO RETENTION option determines recovery.  For example, if the UNDO_RETENTION parameter is set to 2 hours and a user deletes the data by accident at 11 a.m. with a commit done. Using FLASHBACK QUERY, he may then get these rows just until 1 PM.