• How would I set up a Foreign Key between the Job_Request (RequisitionNumber) and the Job_Requisitions(RequisitionNumber) knowing that the first record created will be in Job_Request which will have a null value in the RequisitionNumber column until after the request has been approved and assigned?

    You can have the JobRequest table only reference the JobRequisitions table. The JobRequisitions table can itself play host to the location and job ID's. So in the relational schema this would imply two joins. It keeps things clean.

    It is perfectly acceptable to have a NULL until the actual value is known. Keep in mind I am not talking about warehousing here, just your data in the operational system that your application(s) write to.

    ----------------------------------------------------