You have a workbook that connects to a database.

To schedule a refresh of the data, you need to ensure that Tableau Server or Tableau Online can access the database without prompting for credentials. This can be done by embedding the credentials in the workbook or the published data source. You also need to extract the data from the database and publish it as a separate data source or as part of the workbook. A live connection would not allow you to refresh the data on a schedule, as it would always query the database directly. A hyper file is a format for storing extracted data, but it is not a requirement for scheduling a refresh. References:

Tableau Certified Data Analyst Exam Prep Guide, page 10, section “Publishing and Scheduling Data Refreshes”

Tableau Help: Embedding Database Credentials

Tableau Help: Extract Your Data