ATTACH [DATABASE] filename AS schema-name;

-- Attach another database file
ATTACH DATABASE 'archive.db' AS archive;

-- Query a table in the attached database
SELECT * FROM archive.events WHERE event_date > '2025-01-01';

ATTACH 'customers.db' AS customers_db;

-- Join tables across the main and attached databases
SELECT o.id, o.total, c.name
FROM main.orders o
JOIN customers_db.customers c ON o.customer_id = c.id;

ATTACH ':memory:' AS scratch;