Too Long; Didn't Read
This article uses Exercise number 10 on the Self JOIN SQL ZOO tutorial to teach self JOINs in a beginner-friendly way. The only way to understand SQL problems is to understand the data you're dealing with. The whole business of SQL becomes really abstract if you can't visualize the tables somehow. We need to find the buses that stop at Craiglockhart and have stops in common with the ones they stop at Lochend because that's where they can get off and change.