[jboss-user] [Persistence, JBoss/CMP, Hibernate, Database] - merge detached entity will insert a new entity

em.merge(course); // course is a detached entity I got the following exception: org.hibernate.exception.ConstraintViolationException: could not insert: package.Course. The exception means it tried to insert a new row for merge. The detached entity was initially retrieved from database using course = em.find(Course.class, 876L); // the course id is 876. It has a valid id. (using debugger). If I load the entity from database first, then merge it, it works. em.find(Course.class, 876L); em.merge(course); I have been working on solving this for days. Any helps are appreciated. Thanks Dave View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4044590#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...