FAQ: Code Challenge: Aggregate Functions - Code Challenge 3


#1

This community-built FAQ covers the “Code Challenge 3” exercise from the lesson “Code Challenge: Aggregate Functions”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Web Development
Data Science

FAQs on the exercise Code Challenge 3

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#2

to curriculum developers:
It would have been nice have one or two more hints in the exe before having to go to full solution…


#3

I was able to complete the challenge, but I was curious why COUNT(watch_duration_in_minutes) works and not COUNT(duration). As far as I understand, the ROUND command doesn’t actually change the data in the table, so how was COUNT able to count the rounded values when I specified the original column name, and not the renamed round results?

In other words, why is the below example right?
Correct:
SELECT ROUND(watch_duration_in_minutes, 0) AS duration, COUNT(watch_duration_in_minutes) AS “count” FROM watch_history;

Not correct:
SELECT ROUND(watch_duration_in_minutes, 0) AS duration, COUNT(duration) AS “count” FROM watch_history;


#4

Completely agree with your solution. Not sure why it was shown incorrect


#5

I passed this challenge without order by… why i need it?

-Spoiler-

select
ROUND(watch_duration_in_minutes)
as ‘duration’,
count(watch_duration_in_minutes)
as ‘count’
from watch_history
group by 1

;


#6

As far as I can understand, the “rename process” in order to be completed (by using SELECT… AS…), we have to write the whole command , I mean finish the command by writing the name of the table (FROM watch_history).
So, COUNT (duration) cannnot be identified since the new name (duration) has not been applied yet (the command SELECT … AS is still incomplete).
On the other hand, in whichever command (GROUP BY, ORDER BY) is written afterwards, the new name (duration) can be used.