Movie er diagram superclass and subclass

#MOVIE ER DIAGRAM SUPERCLASS AND SUBCLASS HOW TO#

There is a technique you could benefit from, called 'shared primary key'. This is sometimes called 'class table inheritance'. It all depends on which way seems simpler and clearer to you and to others who look at the diagram.ДЄs far as tables go, you could have three tables, just as you have shown. Then a single line connects the gen/spec box with the Employees table. The following sample shows one way to depict a gen/spec case. Instead, they would go to something I'll call a gen/spec box. The lines leading out of Managers and Drivers would not go separately to Employees. The first is how do you want to draw the diagram, and the second is how do you want to design the tables.ДЄs far as drawing the diagram goes, I would draw it the same way you have, with one exception. It's really the same thing as what object models call 'superclass/subclass' as you have done. This is a case of what's called 'generalization/specialization' in ER lingo.

So, how can I represent accurately this sort of relationship in my diagram?

Each attribute in EMPLOYEE applies to MANAGER and DRIVER, but MANAGER and DRIVER will have some extra attributes that are not characteristics of the EMPLOYEE entity type (or table, once it is implemented).

I am new to this, so I am not sure whether I have to type out all the attributes 1 again in the subclass entities (or subtypes), i.e., MANAGER and DRIVER, or whether I there is a way of connecting to and grabbing the attributes from the superclass (or supertype) so that it is more clear that they relate, something like a FOREIGN KEY, I guess.ДЎ.

#MOVIE ER DIAGRAM SUPERCLASS AND SUBCLASS HOW TO#

I am trying to figure out how to represent a one-to-one (1:1) relationship regarding a superclass/subclass or supertype-subtype structure in an entity-relationship diagram (ERD) of the kind created by means of MySQL Workbench (which, as you know, looks more close to a concrete SQL implementation than an original P.

Movie er diagram superclass and subclass