SQL Issue: Question about the MINUS / INTERSECT operators

Hi All,

Calling all SQL gurus: I have a question about the MINUS / INTERSECT operators and was hoping to get help on a tricky SQL issue.

ASK 1: Run the two sub-queries below and do a diff or intersection on the tifa column as shown. A standard MINUS / INTERSECT operator does the job as follows.

QUERY 1

SELECT COUNT(e.tifa)
FROM (
          (SELECT DISTINCT e.tifa
           FROM ctv_app_launch e
           WHERE (e.country_code = 'US'
                  AND e.app_id = '11101200001'
                  AND e.event_time BETWEEN '2020-07-26 00:00:00.0' AND '2020-10-01 23:59:59.999')
           GROUP BY e.tifa
           HAVING COUNT(*) > '0' 

           MINUS -- (or INTERSECT)

           SELECT DISTINCT e.tifa
           FROM exposure_events e 
           WHERE (e.type = '1'
                  AND e.timestamp BETWEEN '2021-01-17 00:00:00.0' AND '2021-02-15 23:59:59.999'
                  AND e.country_code = 'CA'
                  AND e.content_id = '78354867415943449')
           GROUP BY e.tifa)) e

ASK 2: Do the same query as ASK 1 but also keep track of the associated "maximum timestamp" per e.tifa

QUERY 2 (not working as expected)

SELECT DISTINCT e.tifa,
                MAX(ts) AS max_timestamp
FROM (
          (SELECT DISTINCT e.tifa,
                           MAX(e.event_time) AS ts
           FROM ctv_app_launch e
           WHERE (e.country_code = 'US'
                  AND e.app_id = '11101200001'
                  AND e.event_time BETWEEN '2020-07-26 00:00:00.0' AND '2020-10-01 23:59:59.999')
           GROUP BY e.tifa
           HAVING COUNT(*) > '0' 

           MINUS -- (or INTERSECT)

           SELECT DISTINCT e.tifa,
                           MAX(e.timestamp) AS ts
           FROM exposure_events e
           WHERE (e.type = '1'
                  AND e.timestamp BETWEEN '2021-01-17 00:00:00.0' AND '2021-02-15 23:59:59.999'
                  AND e.country_code = 'CA'
                  AND e.content_id = '78354867415943449')
           GROUP BY e.tifa)) e
GROUP BY e.tifa

PROBLEM: Even though the number of columns in the two sub-queries is the same, what will be MINUS-ed or INTERSECT-ed is not the same. I want the MINUS or INTERSECT to happen on the e.tifa (from both sub-queries) and then intelligently pick where the ts comes from, either e.event_time or e.timestamp depending on where the e.tifa came from.

I hope I was able to explain my situation and that some gurus can help me out!