Unfortunately, I can't say this made it easier to visualize how joins work. How do you visualize a cartesian product filtered through join predicates, the result of which is filtered through a where clause?
It sounds doable, but come query time, I always get a surprise or five before I see the result I was expecting. Actually, if I'm being honest, it's a lot more than five. Granted, I'm not simply tacking customer names onto purchase orders, but if you're building a real-world application, queries graduate from tutorial material-level very early on.
Unfortunately, I can't say this made it easier to visualize how joins work. How do you visualize a cartesian product filtered through join predicates, the result of which is filtered through a where clause?
It sounds doable, but come query time, I always get a surprise or five before I see the result I was expecting. Actually, if I'm being honest, it's a lot more than five. Granted, I'm not simply tacking customer names onto purchase orders, but if you're building a real-world application, queries graduate from tutorial material-level very early on.