jpa实现插入和更新操作（字段有值就更新,没值就用原来的）

@Data
    @Entity
    @Table(name = "kp_customers")
    public class Customers {

        @Id
        //插入时候因为主键自增，导致不能丝滑插入，需要在实体类的头上加上如下注解，完成愉快的插入。
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id")
        private long id;

        @Column(name = "manager_id")
        private long managerId;
    }

@Transactional
    @Override
    public int updateLove(LoveParam param) {
        if (param.getManageId() == 0 || param.getProjectId() == 0) throw new ArithmeticException("缺少必要参数");

        Optional<makeLove> optional = LoveRepository.findById(param.getLoveId());
        if (!optional.isPresent()) {
            makeLove makeLove = new makeLove();
            makeLove.setProjectId(param.getProjectId());
            makeLove.setLoveName(param.getName());
            makeLove.setLovePhone(param.getPhone());
            makeLove.setAddTime(new Timestamp(System.currentTimeMillis()));
            LoveRepository.saveAndFlush(makeLove);
        } else {
            LoveRepository.updataLoveById(param);
        }
        return 520;
    }

这一段jpa的更新操作之所以能令妙龄少女春心荡漾，余味绕梁，柔情似水，千姿百魅，妙就妙在其字段有就更新，没有就不更新.
而saveandflush虽然也可以插入更新两用，但是在字段没有的情况下就会更新为空，破坏了之前的原有字段！

@Modifying
    @Transactional
    @Query("update Loves u set " +
            "u.managerId = CASE WHEN :#{#param.manageId} IS NULL THEN u.managerId ELSE :#{#param.manageId} END ," +
            "u.projectId = CASE WHEN :#{#param.projectId} IS NULL THEN u.projectId ELSE :#{#param.projectId} END ," +
            "u.idCard = CASE WHEN :#{#param.idCard} IS NULL THEN u.idCard ELSE :#{#param.idCard} END ," +
            "u.LoveName = CASE WHEN :#{#param.name} IS NULL THEN u.LoveName ELSE :#{#param.name} END ," +
            "u.LovePhone = CASE WHEN :#{#param.phone} IS NULL THEN u.LovePhone ELSE :#{#param.phone} END ," +
            "u.LoveHouse = CASE WHEN :#{#param.houseNo} IS NULL THEN u.LoveHouse ELSE :#{#param.houseNo} END ," +
            "u.intentionIndex = CASE WHEN :#{#param.intentionIndex} IS NULL THEN u.intentionIndex ELSE :#{#param.intentionIndex} END " +
            "where u.id = :#{#param.LoveId}")
    Integer updataLoveById(@Param("param") LoveParam param);