There are several ways in which database records can be changed or added. In the builder interface it is possible to do this by going into the databases module. All the databases currently in the system will appear with a button next to them to Add/Edit Records.
After clicking on that, all the records in that database will show. An Options drop-down at the top allows builders to create new records. Within the builder interface it is only possible to add database records on an individual basis; the user interface must be used for importing database records.
When a user views a database field and has Write permission for the database, they will see a button, next to Add, called View All. This button will take users to a similar page to what the builder sees when selecting Add/Edit Records using the databases module in the builder interface, with just one difference: an Import button will appear in the Options drop-down. Similar to importing data to an event form, users can upload a CSV file with new database records. The Add button will take users straight to creating a new record for the database.
You can read the Managing Databases article for more details on how a user can interact with a database, including importing records into a database.