Method of updating a database of a navigation device and navigation device associated thereto

To update a database (3) of a navigation device (1) which stores at least a base version (6) of a digital map, versions (6-8) of the digital map which are available locally in the database (3) or remotely from the navigation device (1) are identified. To execute the navigation task, a version (7, 8) of the digital map is selected for execution of the navigation task. Data from a sub-set of storage blocks in which the selected version is stored is required to execute the navigation task. Depending on whether all storage blocks of the sub-set are already stored locally in the database (3), data stored in storage blocks of the sub-set which are not yet stored locally in the database (3) are downloaded via a wireless interface. The downloaded data are stored in the database (3) without modifying the base version (6) of the digital map.