Java Spring Jpa中多对多关系的查询

如果可能的话，我想用Spring数据Jpa进行多对多关系的查询（因为查询会很长）。这是我的实体：

@Entity
public class Rental extends BaseEntity<Long> {
    private int price;
    private long clientId;
    private long gunTypeId;
}

但我得到了一个错误：

---

org.springframework.orm.hibernate5.HibernateSystemException:没有JDBC类型的方言映射：2002；嵌套的异常是org.hibernate.MappingException:JDBC类型没有方言映射：2002

您可以尝试类似@Query（“选择r.gunTypeId，从Rentals中计数（r）按组（r.gunTypeId）按计数顺序（r）限制1”）的操作吗？这样我就有一个方言错误。我在问题中加了它，如果你能帮我的话

public GunType getMostRentedGunType() {
        log.trace("getMostRentedGunType: --- method entered");
        try {
            Map<Long, Integer> count = new HashMap<>();
            this.getAllRentals().forEach(rental -> {
                count.put(rental.getGunTypeId(), count.getOrDefault(rental.getGunTypeId(), 0) + 1);
            });

            var max = count.entrySet().stream()
                    .max((entry1, entry2) -> entry1.getValue() > entry2.getValue() ? 1 : -1)
                    .get()
                    .getKey();
            var result = gunTypeRepository.findById(max).orElse(null);
            log.trace("getMostRentedGunType: result={}", result);
            return result;
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }

@Query(value = "select gt from guntype gt where gt.id in (select r.guntypeid from rental r group by (r.guntypeid) order by count(r) desc limit 1)", nativeQuery = true)
    GunType getMostRentedGunType();