错误栈：
org.zkoss.zk.ui.UiException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed: at [file:/C:/Users/lyg21_000/git/Saas/target/classes/main.zul, line:26]
at org.zkoss.bind.impl.MiscUtil.mergeExceptionInfo(MiscUtil.java:175) ~[zkbind-7.0.4.jar:7.0.4]
at org.zkoss.bind.BindComposer.doBeforeComposeChildren(BindComposer.java:161) ~[zkbind-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.impl.UiEngineImpl.doBeforeComposeChildren(UiEngineImpl.java:930) ~[zk-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild0(UiEngineImpl.java:869) ~[zk-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:826) ~[zk-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreate0(UiEngineImpl.java:735) ~[zk-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.impl.UiEngineImpl.execCreateChild(UiEngineImpl.java:797) ~[zk-7.0.4.jar:7.0.4]
at org.zkoss.zk.ui.imp