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The task was - https://platform.stratascratch.com/coding/514-marketing-campaign-success-advanced/official-solution?code_type=1

And I'm a little bit confused in the code.

 SELECT user_id
 FROM marketing_campaign
 GROUP BY user_id
 HAVING count(DISTINCT created_at) > 1
    AND count(DISTINCT product_id) > 1)

I'm interested in HAVING, default code would be like 'select user_id, count(DISTINCT created_at), count(DISTINCT product_id) and something like this, but in this code its added to HAVING. Does this mean count(DISTINCT created_at) work in the ALL DATASET? BUT HOW IF ITS ALREADY GROUP BY background and then return only user_id which one like this condition?

Improve this question
4
  • For each user_id, check the HAVING clause! I.e. only return user_id's having more than 1 distinct created_at and also more than 1 distinct product_id. Commented Dec 21, 2023 at 9:58
  • HAVING claus will do this for the entire original data array, not for the aggregated? Commented Dec 21, 2023 at 10:02
  • Please read minimal reproducible example Commented Dec 21, 2023 at 11:28
  • HAVING works per grouping, so in this case per user_id Commented Dec 21, 2023 at 12:58
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