JBoss supports the tag hibernate.hbm2ddl.auto to define if your tables are created or udpated during redeployment. I chose create-drop to have them dropped after each undeployment, so that they can be nicely recreated. The option update does not work sometimes. When you undeploy (EX:restart JBoss) , the table "book" is dropped. That causes the warning comes out. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4108785#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...