article3.sql

WITH daily AS (
    SELECT
        DATE(created_at) day,
        user_id
    FROM
        `example-project.ivan.article_example_dataset`
)
SELECT
    day,
    SUM(APPROX_COUNT_DISTINCT(user_id)) OVER (ORDER BY day ROWS BETWEEN 89 PRECEDING AND CURRENT ROW) ninty_day_window_approx
    FROM
        daily
    GROUP BY
        1
    ORDER BY
        1 DESC;