Spring boot使用save()方法執行更新時，沒有指定的字段在數據庫顯示為null，什么原因，請指教@PutMapping(value?=?"/stu/{id}") public?Student?stuUpdate(@PathVariable("id")?Integer?id, ?????????????????????????@RequestParam("name")?String?name, ?????????????????????????@RequestParam("age")?Integer?age)?{ ????Student?student?=?new?Student(); ????student.setId(id); ????student.setName(name); ????student.setAge(age); ????return?stuRepository.save(student); }@Id @GeneratedValue private?Integer?id; private?String?name; private?Integer?age; private?String?size;