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As you can see in the following image, the user interface of my app has a total of 12 text boxes (6 text boxes in each part) in the seller and buyer sections.
The image below is a part of the ERD relating to this application's database; since the relationship between these two tables is one-to-many, an additional entity (Seller ID) is defined in the Buyer detail table in comparison to the user interface.
When a user enters data from the UI, I want the Seller ID value to be automatically inserted into the database.
Based on the above explanation, is this type of application design (user interface and ERD) correct?
If this approach is not correct, please provide a standard approach that keeps to ERD design principles and clean code.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(291.2, 11%, 38%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EHL%3C/text%3E%3C/svg%3E)
Hi,@Reza Jaferi .Welcome to Microsoft Q&A Forum. You could try to see if the following relationships meet your needs.
Relationships:
One-to-Many relationship between Seller and Invoice:
Seller (1) -----< (Many) Invoice
One-to-Many relationship between Buyer and Invoice:
Buyer (1) -----< (Many) Invoice
Many-to-Many relationship between Product/Service and Invoice:
Product/Service (Many) -----< (Many) InvoiceLineItem (Join Table) >----- (Many) Invoice
Many-to-One relationship between Product/Service and Seller:
Seller (1) -----< (Many) Product/Service
Many-to-One relationship between Product/Service and Buyer:
Buyer (1) -----< (Many) Product/Service
Here, I introduced an additional entity called InvoiceLineItem to represent the many-to-many relationship between Product/Service and Invoice. This join table captures the relationship between products/services and invoices.
Thanks for the reply. I have uploaded the database link to GitHub (question updated). Please apply the same description to the database and upload it as an answer for me to accept and rate.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(211.20000000000002, 61%, 30%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EBS%3C/text%3E%3C/svg%3E)
the first question is can a buyer buy from two different sellers? can a buyer have more than one order? it sees like the buyer/seller relationship would be at the order level.
the first question is can a buyer buy from two different sellers?
1st: no
can a buyer have more than one order?
2nd: yes
Could you possibly draw the ERD for my app based on the UI (all the details included, as seen in the image below)?
so your saying a Customer can only order from the same seller, they can never create an order for a different seller.