What is the minimum information necessary to update contracts

Summary:

Trying to create a data model and report to fix contracts that are missing PERIOD_OF_SERVICE_ID.I can run an SQL query on any of the tables, filter by PER_CONTRACTS_F.ASSIGNMENT_ID = PER_ALL_ASSIGNMENTS_M.ASSIGNMENT_ID to get the work terms table or PER_CONTRACTS_F.ASSIGNMENT_ID = PER_ALL_ASSIGNMENTS_M.WORK_TERMS_ASSIGNMENT_ID to get assignment table and getting period of service ID from either of them but I do not have source system ID or source system owner to merge with the current contracts.

Is there an SQL that I can use that pulls only the required information and I can directly upload as a HDL so that I can merge with the current contracts without any issues?