update_streak.sql

UPDATE streaks
SET current_streak = (
    CASE
        WHEN %(date)s - last_checkin_dt = 1 THEN current_streak + 1
        ELSE 1
    END
),
longest_streak = GREATEST(longest_streak, (
    CASE
        WHEN %(date)s - last_checkin_dt = 1 THEN current_streak + 1
        ELSE 1
    END
)),
last_checkin_dt = %(date)s
WHERE user_id = %(user_id)s AND %(date)s > last_checkin_dt
RETURNING *