About including differential backups in a restore operation
If you incorporated differential backups in the backup strategy, the restore process differs depending on the type of backups available.
Determine how to perform the restore based on which of the following differential backups you have:
If differential backups were made after the last full database backup, restore the last database backup that is followed by the most recent differential backup. Then apply all subsequent transaction logs.
If no differential backups were made since the last full database backup, restore the last full database backup and then apply all subsequent transaction logs.
If several differential backups are available but the latest one cannot be read, restore the most recent full database backup. And restore the latest readable differential backup and apply all subsequently created transaction logs.