I found a couple of styrofoam models for: Windows 95 and Lotus Notes (if that helps) Actually, here’s a Tom Love case study that shows a couple of his models. This model may represent the least expensive CASE tool on the market — materials cost $20.35. It was more useful than any CASE tools I … Read more
It refers to a “Purchase Order” which typically consists of one or more lines, called “Order Lines”. As almost every business on earth has some similar record of it’s orders, purchases and/or sales, it has been the canonical real-world data example of a Parent-Child (or Master-Detail) relationship for as long as databases have existed (well … Read more
Caveat Lector As Datomic is new and my experience with it is limited, this answer shouldn’t be considered best practices in any way. Take this instead as an intro to Datomic for those with a relational background and a hankering for a more productive data store. Getting Started In Datomic, you model your domain data … Read more
I think n.piskunov is on the right track. I would use it as the mathematical analogy found here: https://math.stackexchange.com/questions/247380/analogy-between-one-and-only-one-and-if-and-only-if “existence of at most one such X that satisfies Y.” As an example, consider these relations: A student, Alice, can only have one dorm room at at time. A dorm room can only house one student … Read more