Consider the table below:

case_id long
case_dt date
reference_num string

In this table, case_id is generated and unique. Each row contains a value in the reference_num column and sometimes the value will be the same for many rows -- this represents related cases.

What is the preferred way to represent this? Is there a mapping that would work? It looks similar to the one-to-many Cats/kittens example in the doc, but in this case, the value for referenece_num is the not the same value as the primary key (case_id)

Thanks,
John