Freitag, 1. Februar 2008
Mittlererweile bin ich Autobesitzer und habe Kinder. Eine Situation, die Probleme löst und zukünftige schaffen kann. Deswegen habe ich auch mit Interesse diesen Artikel gelesen. Der Autor hat offensichtlich in diesem Bereich wesentlich mehr Erfahrung als ich:
Before we can show you the contents of our pair of mapping files, we need to explain our very simple data model and application. Our application is concerned with a small family - a husband, Jack; a wife, Jill; and their son, James - who own four cars among them. The reason they own four cars is that one of the cars, a sporty car owned by James, is often in the shop for repairs. James has a tendency to have accidents for which others - never he - is responsible, and the accidents amazingly tend to occur when he is driving that specific car. Note that no member of this family is permitted to drive each other's cars - the attachment to their own car is too great. As a result, there is a one-to-many association between a Driver and the Cars that driver may drive. (In most families, the association would probably be many-to-many, but in the family in our example it is one-to-many.) Nothing stops this family from conceivably purchasing additional cars, but due to the prevailing family dynamics in their family, no member will ever drive each other's cars.