An incremental backup is a type of online backup. An incremental backup is a backup of the transaction log only and can only be used for recovery if you have run a full backup before running the incremental backup. Full backups can be interspersed with several incremental backups.
The backup copies of the database file and transaction log file have the same names as the online versions of these files. For example, if you make a backup of the database created during installation, the backup copies are called esp_cluster.db and esp_cluster.log. When you repeat the backup statement, choose a new backup directory to avoid overwriting the backup copies.
The following statement creates an incremental backup of the database in the directory C:\temp\backup:
BACKUP DATABASE DIRECTORY 'c:\\temp\\backup' TRANSACTION LOG ONLY TRANSACTION LOG TRUNCATE;