2

I am practicing drawing entity-relationsip diagrams and in the example it states "many employees work on a project, and employee can work many projects but can only be assigned to at most one project at a given time." Does the final statement after the "but" mean that there is another relationship?

2

It means that time is an essential component of the relationship. It's telling you that there's a functional dependency (employee, time) -> project.

In an entity-relationship diagram, I might model it like so:

Assignment weak associative entity

I made it a weak entity dependent on Employee and with time as a weak key, but it's still a relationship between Employee and Project, hence a weak associative entity.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.