text: CREATE TABLE serviced_organisations (
      serviced_organisation_code TEXT PRIMARY KEY,
      name TEXT
  );
  
  CREATE TABLE serviced_organisation_working_days (
    serviced_organisation_code TEXT NOT NULL REFERENCES serviced_organisations (serviced_organisation_code),
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    PRIMARY KEY(serviced_organisation_code, start_date, end_date)
  );
  
  ALTER TABLE vehicle_journeys ADD COLUMN non_operation_serviced_organisation_code TEXT NULL;