JavaEE : Does EntityManager get method changing state in DB

Question

我想知道是否可以对该本地列表中的每个元素执行 em.remove ？此代码是否会更改数据库中的状态？

TypedQuery<Product> query = em.createNamedQuery("Product.findByCode", Product.class);
query.setParameter("code", code);
List<Product> productList= query.getResultList();
   for (int i = 1; i < productList.size(); i++) {
      em.remove(productList.get(i));
   }

Answer 1

是的，它改变了数据库，因为那是他的工作。

The EntityManager API is used to create and remove persistent entity instances, to find entities by their primary key, and to query over entities.

https://docs.oracle.com/javaee/7/api/javax/persistence/EntityManager.html