Hi


Basically Im having trouble with an Entity Relationship Diagram (ERD), for an assignment. The ERD is based on a simple scenario, I have attempted it a few times and the lecturer says its not right.

what's wrong with the part in red, in your own words?

where are your constraints? (primary keys and foreign keys)

Thanks for taking a look.

Below is a link to a updated erd with all the attributes and primary/foreign keys.

neither am i

in words, what does one instance of this entity represent? what is that pk made of? it looks like it might be an auto_increment, and generally speaking, you should never have an auto_increment for a relationship table

see what you can do if that table were completely eliminated

sorry about the basic diagram dont have access to proper ERD design tool at home.

One would think that colleges could sure come up with better real life examples to model. ..driver skill?? I personally don't see where that ties into an order.

fjm1967

Do you have any sudgestions?
Basically i just want a quick solution so i can get the schema finished and build for oracle database and get the assisgnment out the way.

I can give you my opinions about your model but r937 is the one you want to listen to.

Do you have the option of totally removing the skill entity or did your instructor tell you that you had to have it? I don't understand what driver skill has to do with an order.

Basically the instructor gave the scenario and the entitys



Then we have to come up with a working model

But i would be happy for any input you could offer me.

I do appriciate time given.

Ok, I will give you my take on how it should be based on what your instructor said. brb.

This is how I would model it. I would remove the three entities you have for the special vehicles. You can use the vehicle type column in the vehicle entity to track that.

Because of this, I simply associated the chauffer's skill set with the driver. I am assuming that the "skilled vehicle driver" entity is only a record of the skill levels that a driver can have.

you are not going to get that here

we do not do homework assignments

however, we will help you do yours by asking you questions

you still have to do all the work, though

oops.. I missed that..

Cheers fjm1967

I understand your solution to the scenario.

Does anybody else agree or disagree with fjm1967 opionion's to my model or anythink else they can add.

r937 what do you think?

Cool thats fine with me.
Ive been at it for 3 weeks and i was only really asking for asistance, I learn through examples and this is the first one ive attempted.
In my oppion data modeling is not clear cut. Its more on the oppions of erd designer. That is basically what i was asking for.