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Mike Booth
2,035 PointsCalculating Averages
What if I wanted to use the group by, but also wanted to order it in descending order with the highest cost avg first? I tried using group by and order by but it threw an error
2 Answers
Randy Layne
Treehouse ModeratorI think this might be the query you are looking for:
SELECT AVG(cost) as average, user_id FROM orders GROUP BY user_id ORDER BY average DESC;
Ari Misha
19,323 PointsHiya Mike! There is a difference between "GROUP BY" and "ORDER BY", which i think is a really important concept.
"ORDER BY" alters the order in which items are returned.
"GROUP BY" will aggregate records by the specified columns which allows you to perform aggregation functions on non-grouped columns (such as SUM, COUNT, AVG, etc).
Here is the example to make it more understanding and concise:
TABLE:
ID NAME
1 Peter
2 John
3 Greg
4 Peter
SELECT *
FROM TABLE
ORDER BY NAME
=
3 Greg
2 John
1 Peter
4 Peter
SELECT Count(ID), NAME
FROM TABLE
GROUP BY NAME
=
1 Greg
1 John
2 Peter
SELECT NAME
FROM TABLE
GROUP BY NAME
HAVING Count(ID) > 1
=
Peter