org.hibernate.exception.GenericJDBCException: could not insert:

错误信息：15:34:09,937  INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:155 - Running hbm2ddl schema update
15:34:09,938  INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:167 - fetching database metadata
15:34:09,940  INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:179 - updating schema
15:34:09,944  INFO org.hibernate.tool.hbm2ddl.DatabaseMetadata:119 - table not found: loginandregister_ssh
15:34:09,944  INFO org.hibernate.tool.hbm2ddl.DatabaseMetadata:119 - table not found: loginandregister_ssh
15:34:09,945 DEBUG org.hibernate.tool.hbm2ddl.SchemaUpdate:203 - create table loginandregister_ssh (id integer not null auto_increment, password varchar(255), username varchar(255), primary key (id))
15:34:09,945 ERROR org.hibernate.tool.hbm2ddl.SchemaUpdate:212 - Unsuccessful: create table loginandregister_ssh (id integer not null auto_increment, password varchar(255), username varchar(255), primary key (id))
15:34:09,945 ERROR org.hibernate.tool.hbm2ddl.SchemaUpdate:213 - No database selected
15:34:09,946  INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:217 - schema update complete
Hibernate: 
    insert 
    into
        loginandregister_ssh
        (password, username) 
    values
        (?, ?)
15:34:10,036  WARN org.hibernate.util.JDBCExceptionReporter:100 - SQL Error: 1046, SQLState: 3D000
15:34:10,037 ERROR org.hibernate.util.JDBCExceptionReporter:101 - No database selected
Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not insert: [com.dqgb.Entity.User]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:64)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2176)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2656)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:321)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:563)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:551)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:547)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:342)
at $Proxy7.save(Unknown Source)
at com.dqgb.test.test.main(test.java:27)
Caused by: java.sql.SQLException: No database selected
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1078)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4187)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4119)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2570)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2815)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2458)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2359)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:94)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)
... 22 morehibernate.cfg.xml<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>    <session-factory>        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <property name="format_sql">true</property>        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">update</property>        <mapping class="com.dqgb.Entity.User"/>
    </session-factory></hibernate-configuration>Entity类package com.dqgb.Entity;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;@Entity
@Table(name="loginandregister_ssh")
public class User {
private int id;
private String username;
private String password;
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}

public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}DAOpackage com.dqgb.test;import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;import com.dqgb.Entity.User;public class test { public static void main(String[] args) {

User user = new User();

user.setUsername("1111"); 
user.setPassword("1111");

Configuration cfg = new AnnotationConfiguration();
SessionFactory sf = cfg.configure().buildSessionFactory();
Session session = sf.getCurrentSession();
session.beginTransaction();
session.save(user);
session.getTransaction().commit();
session.close();
sf.close();
}}