I’m confused about what the behavior of a polymorphic relation would be.

My question is if we add a column invoiceId on table InvoicePaymentMapping, which relates to two tables sales_invoice and purchase_invoice, and try to find a row with invoiceId 3.

Assume we have a row with id 3 in both the tables sales_invoice and purchase_invoice. What will happen?

What is the proper way to do this if it is not the right way?

My sample schema looks like this.

model InvoicePaymentMapping {
  id  Int    @id @default(autoincrement())

  invoiceId Int @map("invoice_id")
  purchaseInvoice PurchaseInvoice?   @relation(name:"invoice_payment_mapping_purchase_invoice_mapping", fields: [invoiceId], references:   [id], onDelete: Restrict, onUpdate: Cascade, map: "purchase_invoice_id")
  salesInvoice SalesInvoice? @relation(name: "invoice_payment_mapping_sales_invoice_mapping", fields: [invoiceId], references: [id], onDelete: Restrict, onUpdate: Cascade, map: "sales_invoice_id")
}