Question

I was wondering what the answer should be for 1c. on this website:

http://sqlzoo.net/6.htm

SELECT company 
FROM route WHERE stop=4
GROUP BY name, ID

this obviously isn’t working, the ID and name isn’t showing up no matter what. What is missing here? Thanks.

Answer 1

SELECT stops.id, stops.name
FROM route 
INNER JOIN stops on route.stop = stops.id
WHERE route.num = 4 AND route.company = 'LRT'

You need to join the tables as the data you want to return is in a different table to the one which filters the data.