Conceptual and Logical database design

[vinsbg]

Hi,
sorry for my newbie question but I can't understand what is the different between Logical and Conceptual database design. Can you provide me with some samples for those two types of design?

Also what design is generated with MySQL Workbench for example when you import database schema? Is it Logical?

[Traevel]

Sounds homeworky so just a hint to get you started: it's all in the details.

There is also a physical model by the way.

[vinsbg]

Yes, this is for my project. So as I understand in conceptual design tables are "objects" and I just show connections between them. In logical model I show same as conceptual + their primary, foreign keys and the relations between them. In physical are keys, tables name, columns etc.. but without relations.

So if I understand correctly in physical model I don't need to show connections just tables, names and types.
In this what I generate with MySQL Workbench should be Logical model.

Am I right? I don't want someone to make my models and schemas.. I just needed a little clarifications on this. Thank's

[Traevel]

I would include relations in physical. Especially since they could be different due to the physical situation. A logical model is as detailed as you can get it without the physical implementation. In other words, whether you are designing for MySQL or Oracle should make no difference in the logical model. That will be covered in the physical model.

Hi winsbg,

A typical logical model in database design is the Entity Relationship Model (ERM) by Peter Chenn. A typical physical design is the implementation of an ERM on a specific database system, also known as Relational Model (RM), e.g. creating of tables, keys, access paths, etc. As for MySQL the workbench is to design a logical Model using EER-Modelling (MySQL-specific ERM). After then you can create a RM containing all table-, key- and index-creations automatically drawn from your EER. I hope that will help you.

1STDAN

As for relations: First, logical design based on ERM has one-to-one, one-to-many and many-to-many relationships. They may be mapped into the physical model by applying foreign keys. For example, a many-to-many relationship between two sets of entities will be mapped into an extra coupling table on RM, where the primary keys of the related both entities become foreign keys and additionally primary keys of the coupling table to express many-to-many of a logical relationship.

1STDAN