How can I improve this basic ERD of 8 entities?

I am creating an ERD. I have 8 entities so far but I know I've got a long way to go. I think I want to split up orders and purchase orders but not sure in what way. Should I make 3 or 4 entities total out of the orders  and purchaseorders entities?

What else can I do to make this more realistic and correct?
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slightwv (䄆 Netminder) Commented:
I this for a school assignment?

As far as sales orders and purchase orders, I might lean towards a generic order entity then have sales and purchase attributes broken out into their own entity.

So an order can only contain one product?

Then there are things like people and places.  I tend to want to keep them the same.  Maybe a person and address entity with a 'type' flag indicating what entry is what.
Mark_CoAuthor Commented:
Yes, I am learning how to make ERDs for my portfolio. So you suggest I turn those 2 entities in to 3: sales, purchases, and orders?
slightwv (䄆 Netminder) Commented:
>>So you suggest I turn those 2 entities in to 3: sales, purchases, and orders?

Maybe more.  It depends.

>>I am learning how to make ERDs for my portfolio

How far have you studied thus far?  Are you VERY familiar with the rules of normalization?

If you don't have a real good grasp of at least up to 3NF, I would suggest you really dig into it until you understand what it is saying.

The standard saying when normalizing data is:
"The key, the whole key, and nothing but the key, so help me Codd."

Until you understand what that means, it can be pretty hard.

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Mark_CoAuthor Commented:
Ok thank you. I appreciate it
slightwv (䄆 Netminder) Commented:
Did you really want to close this out this quick?

There are likely other Experts that will have input as well.

If you would like to have this re-opened so they can post, just let me know.  I can take care of that for you.
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