An incremental backup is a backup of the transaction log file only. Typically, you should make several incremental backups between each full backup.
For more information about the difference between a full backup and an incremental backup, see Types of backup.
Ensure that you have DBA authority on the database.
Make a backup of your transaction log only, not your database file.
For more information about how to perform the backup operation, see:
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 sample database, the backup copies are called demo.db and demo.log. When you repeat the backup statement, choose a new backup directory to avoid overwriting the backup copies.
For more information about how to make a repeatable incremental backup command by renaming the backup copy of the transaction log, see Renaming the backup copy of the transaction log during backup.