SELECT decode(nvl(vo_person_category.oc_calendar_id,vehicle_owner.oc_calendar_id), NULL,person.oc_calendar_id)
FROM person person, vehicle_owner vehicle_owner, vo_person_category vo_person_category
WHERE person.vo_person_category_id = vo_person_category.vo_person_category_id
AND vo_person_category.vehicle_owner_id = vehicle_owner.vehicle_owner_id;


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SELECT vehicle_owner_id, numberplate, company_nr
FROM vehicle
WHERE vehicle_owner_id = (SELECT vehicle_owner_id
                                    FROM vehicle_owner
                                    WHERE UPPER(company_name) LIKE UPPER('%PUTMAN%'))
AND vehicle_id IN (SELECT vehicle_id
                        FROM gu_vehicle
                        WHERE gui_user_id = 101001);