18th February 2021
Datasette 0.55 adds support for cross-database SQL queries. You can now run datasette --crossdb one.db two.db
and then run queries that join data from tables in both of those database files - see cross-database queries in the documentation for more details.
sqlite-utils 3.6 adds similar features: a db.attach(alias, filepath)
Python API method and --attach alias filepath.db
command-line option, both for attaching additional databases in order to execute cross-database queries.