MARIADB

SELECT YEARWEEK(o.created_at, 3) AS year_week,
       p.category,
       SUM(o.amount_cents) / 100.0 AS revenue
FROM orders o
JOIN products p ON p.id = o.product_id
WHERE o.created_at >= DATE_SUB(CURDATE(), INTERVAL 13 WEEK)
GROUP BY year_week, p.category
ORDER BY year_week, revenue DESC;

SELECT signup_date,
       daily_signups,
       SUM(daily_signups) OVER (
         ORDER BY signup_date
         ROWS BETWEEN 6 PRECEDING AND CURRENT ROW
       ) AS rolling_7d_signups
FROM (
  SELECT DATE(created_at) AS signup_date, COUNT(*) AS daily_signups
  FROM users
  WHERE created_at >= DATE_SUB(CURDATE(), INTERVAL 60 DAY)
  GROUP BY signup_date
) d
ORDER BY signup_date;

SELECT DATE_ADD(CURDATE(), INTERVAL seq.seq DAY) AS day
FROM seq_0_to_29 AS seq
ORDER BY day;