累計(累積和)を計算する snippet

SELECT
    day,
    amount,
    SUM(amount) OVER (
        ORDER BY day
        ROWS UNBOUNDED PRECEDING
    ) AS running_total
FROM daily_sales
ORDER BY day;

Try it in the playground: add a duplicate day and watch the RANGE default give both rows the same total; ROWS fixes the accumulation. Moving 7-day window: ROWS BETWEEN 6 PRECEDING AND CURRENT ROW.