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Databases SQL Reporting by Example Day 1: Joining Tables Subjects in the Big Room

György Varga
György Varga
19,198 Points

Wasn't the question: 'Which subjects are taught in the largest room?'


Check out my solution for the task above:

SELECT subjects.name FROM subjects 
INNER JOIN classes ON subjects.id = classes.subject_id
INNER JOIN rooms ON classes.subject_id = rooms.id
WHERE rooms.id = (SELECT id FROM rooms WHERE rooms.capacity 
                   = (SELECT MAX(rooms.capacity) FROM rooms)) GROUP BY subjects.name;

I think this is the correct solution for this task. Can you please check it?

1 Answer

Ben Deitch
Ben Deitch
Treehouse Teacher

Hey György!

Great job using a subquery to figure out the largest room (rather than hardcoding it like I did)! But you've got one of your joins wrong. On your 2nd join, you're joining a SUBJECT_ID to a ROOM_ID when you want to be doing ROOM_ID to ROOM_ID:

INNER JOIN rooms ON classes.room_id = rooms.id

Hope that helps!

György Varga
György Varga
19,198 Points

Ohh thank you! I meant to join that... I was carless.