title: I tried to update the database by jpa but it wont update or gets duplicate
body: <p>I tried to update the table by jpa.</p>
  <pre><code>CREATE TABLE `MagicnotifyCart` (
      `uuid` VARCHAR(50),
      `userid` BIGINT(20),
      `desired_price` DECIMAL(10,2),
      FOREIGN KEY (`uuid`) REFERENCES `MagicnotifyUuidName` (`key`),
      FOREIGN KEY (`userid`) REFERENCES `User` (`id`)
  );
  </code></pre>
  <p>the table i wanted to update is this one, and i tried to update it by jpa.</p>
  <pre><code>@Transactional
  public void updateDesiredPrice(BigDecimal desired_price, String uuid, int userid){
      MagicnotifyCart magicnotifyCart = cartRepository.findMagicnotifyCartById_UuidAndId_Userid(uuid, userid);
      
      magicnotifyCart.getId().setDesired_price(desired_price);
      cartRepository.save(magicnotifyCart);
  }
  </code></pre>
  <p>by using this, i expect to update desired_price null to desired_price, but it won't update when i try this code.</p>
  <p>I debugged the code and I see magicnotifyCart.getId().getDesired_price() becomes the price as I expected, but when it comes to save the value it won't update.
  What should I do if I want to update the value of desired_price by using jpa?</p>