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i am more familiar with ERD
is erd merely for Database design?
are entities in ERD related to Classes in class diagrams?
entities in ERD mean what in Class diagram?
are these two not related to each other when designing?
please explain me
and thanks
Posted 21-Feb-13 5:15am
Edited 21-Feb-13 20:17pm

1 solution

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Solution 1

Hi.Generally for designing a DataBase you need three Steps:
1-Create Conceptual Data Model like ERD:
Conceptual schema is a permanent description of the
database requirements.
2-Create Logical Data Model(Relational,Normal Form):
The first step in building the logical model is to sit down and create the
model from the requirements.Once the relationships and dependencies amongst the various pieces of information have been determined, it is possible to arrange the data into a logical structure which can then be mapped into the storage objects supported by the database management system. In the case of relational databases the storage objects are tables which store data in rows and columns.
3-Create Physical Model:
A physical model is made up of the tables and other physical objects of your RDBMS.
Now we consider Class Diagram:
A class diagram describes the types of objects in the system and the various kinds of static relationships that exist among them. Class diagrams also show the properties and operations of a class and the constraints that apply to the way objects are connected.
for detemining Entities in ERD you must first search the Nouns.for determining classes in Class Diagram you must act similarly.
i think entity in ERD are the same Classes in class diagram.
i hope my idea help you.
Good luck
deva936 at 22-Feb-13 5:16am
thank u for your explanation since i've been waiting for this.
so are you saying that all entities are classes in class diagram? can i take that?
and is it possible that there are more classes than entities for the same system?
ali rad at 22-Feb-13 7:56am must consider that.after you create classes based on Nouns.consider your Model is complete or not?

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