How to create ER based on PK and CK

General Questions/Discussions
1

Hi,
I have Entity A which has a PK(Order #) and candidate key(Order Sequence #), a unique key which i can use to join some Entities.

I have Entity B which has relationship with Entity A as 1 to Many.

if I define Order # as PK in Entity A then i can make the following ER
Say
Entity A(Order #) ---->> Entity B(Order #)

Say now I want to join the Entity A(Order Sequence #) to Entity C. How can do the following join???

Entity A(Order Sequence #) ---->> Entity C(Order Sequence #)

Since already Entity A(Order #) is PK, the Order # column is being added by default by the tool into Entity C as FK…

Let me know if you have any questions…

Srini

2

Hi Srinik,

By “join”, do you mean the join table in sql, or just to connect things in ERD?

If possible, please provide a real case. It would be better than Entity A, B, C.

Best regards,
Jick

3

I meant in ERD only. Will try to send a realtime example soon

Thanks,
Srini

4

Hi Srini,

We look forward to receiving your sample project.

Best regards,
Jick