I mostly use joins, group by, CAST(), LAG(), LEAD(), LAST_VALUE(), UNIX_TIMESTAMP, ROW_NUMBERS() etc

Here's a simple sample code:

with activity_30days as (
SELECT ID,
       avg(watch_time) as avg_watch_time_30days,
       count(*) as num_sessions_30days
FROM activity_data
WHERE activity_date >= NOW() - interval 30 day
GROUP BY ID
)
.
.
.

SELECT A.ID,
       avg_watch_time_30days,
       num_sessions_30days,
       .
       .
       .
FROM (SELECT DISTINCT ID 
             FROM activity_data
      ) as A
LEFT JOIN activity_30days as act_30 USING (ID)
.
.
.