Date Arithmetic with DATE_DIFF

SQL can calculate the distance between two dates. In DuckDB, `DATE_DIFF` is a convenient way to do that.

SELECT order_id, DATE_DIFF('day', order_date, ship_date) AS days_to_ship
FROM orders

This tells you how many days passed between each order and shipment.

Date arithmetic is useful for lead time, retention, overdue tasks, subscription length, and many other business questions.