Contents
Is ERD object oriented?
To produce a data model (a logical view of the data) the technique of choice has been, and still remains, the entity relationship diagram (ERD). However in Object Oriented Development (OOD), classes are used to group together things (including data) that have similar properties.
What two concepts are Entity Relationship Modelling based on?
ER modelling is based on two concepts: Entities, defined as tables that hold specific information (data) Relationships, defined as the associations or interactions between entities.
What are the key reasons why entity relationship modeling is important?
E-R modeling is a communication tool. It helps the data base designer to develop a good data base that meets the end users and application programmers. Especially, E-R modeling gives a pictorial representation of the database. Thus, the database designer can understand the data base description easily.
Is ERD a UML diagram?
ERD is it’s own thing. It’s not in UML specification. You can download specification PDF from the link. UML is a common notation/language for object oriented modeling and it includes a multitude of diagram types.
How is a relationship represented in an entity model?
A relationship connects two or more entity sets. It is represented by a diamond, with lines to each of the entity sets involved.
Why is the object oriented model so flexible?
The objects with similar functionalities are grouped together and linked to different other objects. Due to inheritance, the data types can be reused in different objects. This reduces the cost of maintaining the same data in multiple locations. The object oriented model is quite flexible in most cases.
What makes an object oriented data model object oriented?
Object Oriented Model Object oriented data model is based on using real life scenarios. In this model, the scenarios are represented as objects. The objects with similar functionalities are grouped together and linked to different other objects.
Can a ER model be converted to an E-R model?
An ER model is generally considered as a top down approach in data designing. The data requirements are easily understandable using an E – R model as it utilises clear diagrams. The E-R model can be easily converted into a relational database.