FAQ: Aggregate Functions - Review

Frequently Asked Questions SQL FAQ
1

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This community-built FAQ covers the “Review” exercise from the lesson “Aggregate Functions”.

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2

When I click " I want to do an even more advanced real-world SQL project.,
The link tells me that I dont have access to that page.
Why?
I am a Pro Learner.
Thank you for reply.

3

I have a question to the HAVING with regard to the fake_apps database.

The following SQL commands show that price = 3.99 contains both apps with download greater and less than 10000.

SELECT name, downloads, price
FROM fake_apps
WHERE downloads > 10000
 AND price=3.99;
--- 7 apps returned
  
SELECT name, downloads, price
FROM fake_apps
WHERE downloads < 10000
 AND price=3.99;
--- 2 apps returned

If I now want to get the average downloads in each price category, I call:

SELECT price, AVG(downloads)
FROM fake_apps
GROUP BY price;

However, if I want to consider apps with downloads above 10000, I would call

SELECT price, AVG(downloads)
FROM fake_apps
WHERE downloads > 10000
GROUP BY price;

Accidenetly I however typed:

SELECT price, AVG(downloads)
FROM fake_apps
GROUP BY price
HAVING downloads > 10000;

Here the entry for price = 3.99 vanishes - but not for any other entry. Why does it vanish?