To avoid duplication I would keep all details in the same table, and identify suppliers within that table. This could be done in several ways, the simplest perhaps being a boolean field called Supplier into which you would enter 1 (yes) if the contact is also a supplier.
Thank you for the reply, yes I agree with your idea. I also want to put the SupplierStatus field on the Contact table.
How should I created the ERD for the portal in the Layout (Contact) to display the products that they have in the rental shop. By using the data from the ProductContact.
Just as you have a relationship between Invoice and Contact using ContactID, you can create another TO based on the Contact table, call it Supplier, and link to it using the ContactID plus a 1 to match to the Supplier field I suggested earlier. I would create a constant field (call it One or something similar) which is populated with the value 1 to use for this purpose.
Thank you. Yes its work.
I tend to have a flag field in contacts that lets me set type(s). If it appears that I have contacts that need several types, I might make a table of contact types (or groups & a join table of memberships to groups). It depends on several factors what works for your purposes.
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Thanks for the comment. How do you create the flag field ?
Thanks for helping me.
I decided to share the file. I hope it will helps the person who need it.
And the next step is going on here
I meant as keywords explained - xomething to designate a record is some way to make it unique.
My further comment was if you get into other "types" of contacts, a single field (even with checkboxes) may or may not work for your needs. At that point you might use a related table (with or without a join).