週/月間隔の日付範囲でグループ化

SELECT
 WEEKOFYEAR(`date`) AS period,
 SUM(clicks) AS clicks
FROM `tablename`
WHERE `date` >= CURDATE() - INTERVAL 4 WEEK
GROUP BY period

SELECT
 MONTH(`date`) AS period,
 SUM(clicks) AS clicks
FROM `tablename`
WHERE `date` >= CURDATE() - INTERVAL 3 MONTH
GROUP BY period