問題:
EntityManager.merge()
can insert new objects and update existing ones. EntityManager.merge()
可以插入新對象並更新現有對象。
Why would one want to use persist()
(which can only create new objects)?爲什麼要使用persist()
(它只能創建新對象)?
解決方案:
參考一: https://stackoom.com/question/4ULw參考二: JPA EntityManager: Why use persist() over merge()?