How did autopsy. db come from?

autopsy how to get the data in autopsy. db?

Sorry I’m not sure exactly what your question is?

The autopsy.db file is created when you create a case in Autopsy, and data is added to it when you add a data source to the case, run ingest modules, and do manual things like tagging data.

autopsy.db is a SQLite database, so if you want to look directly at what data is in there you can use something like SQLite Browser to see all the tables.