1.https://www.logicbig.com/tutorials/java-ee-tutorial/jpa/detached-entity-and-lazy-fetch.html
2.https://www.objectdb.com/java/jpa/persistence/detach
3.https://www.baeldung.com/hibernate-exceptions
4.https://blog.overops.com/5-common-hibernate-exceptions-and-how-to-fix-them/
5.有一本书叫做：More than 70 solutions to common Hibernate problems. 作者是的博客是：https://thorben-janssen.com/