Trying to Retrieve the Specific Ethnicity Record Associated with each Period of Service

Summary:It appears that there is a separate row in table per_ethnicities for each of an employee's period of service. Looking for a query

Content (please ensure you mask any confidential information): For each period of service, the system appears to be creating at least one record in the per_ethnicitiess table. Is there a way to know which row(s) in per_ethnicities is associated with which period of service?

If the employee always chooses the same ethnicity or list of ethnicities, then this should not be a problem, but what if they don't? How would one select the current list of ethnicities for the current period of service (as shown in the Demographic Info screen)