内部异常：com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：未知错误1049

Question

这应该是一件容易的事。我正在使用Eclipselink在JPA中编写玩具应用程序，而不是使用SSL。当实体经理被调用时，我会在下面得到消息。我猜我在我的persistence.xml文件中缺少一个参数，但是这个异常不是很具体。

[EL Info]: 2016-08-23 13:28:04.574--ServerSession(1586463432)--EclipseLink, version: Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd 
    Tue Aug 23 13:28:05 EDT 2016 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. 
... 
    Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown error 1049 
    Error Code: 1049 
@ em= Error message: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException 
    Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown error 1049 
    Error Code: 1049 
    javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException 
    Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown error 1049 
    Error Code: 1049 
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:766) 
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryDelegate.getAbstractSession(EntityManagerFactoryDelegate.java:204) 
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryDelegate.createEntityManagerImpl(EntityManagerFactoryDelegate.java:304) 
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:336) 
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:302) 
    at com.ruleagents.hero.Main.main(Main.java:48) 
    Caused by: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException 
    Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown error 1049 
    Error Code: 1049 
    at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:331) 
    at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:326) 
    at org.eclipse.persistence.sessions.DefaultConnector.connect(DefaultConnector.java:138) 
    at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) 
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.setOrDetectDatasource(DatabaseSessionImpl.java:204) 
    at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:741) 
    at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:239) 
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:685) 
    ... 5 more 
... 
    Exception in thread "main" java.lang.NullPointerException 
    at com.ruleagents.hero.Main.main(Main.java:62) 

这是persistence.xml中

<persistence version="2.1" 
xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"> 
<persistence-unit name="CharacterManager" 
    transaction-type="RESOURCE_LOCAL"> 
    <provider> 
     org.eclipse.persistence.jpa.PersistenceProvider 
    </provider> 
    <class>com.ruleagents.hero.Hero</class> 
    <class>com.ruleagents.hero.Logon</class> 
    <!-- class>com.ruleagents.hero.Stat</class --> 
    <properties> 
     <property name="javax.persistence.jdbc.driver" value='com.mysql.jdbc.Driver' /> 
     <property name="javax.persistence.jdbc.url" 
      value="jdbc:mysql://localhost:3306/CharacterManager" /> 
     <property name="javax.persistence.jdbc.user" value="root" /> 
     <property name="eclipselink.ddl-generation" value="drop-and-create-tables" /> 
     <property name="eclipselink.ddl-generation.output-mode" value="database" /> 
     <property name="useSSL" value="false" /> 
     <property name="javax.persistence.jdbc.user" value="root"/> 
    </properties> 
</persistence-unit> 
</persistence> 

，这是它怎么叫：

public static EntityManagerFactory getEMF(){ 
    try { 
     if (emf == null){ 
      emf = Persistence.createEntityManagerFactory("CharacterManager"); 
... 
EntityManager em = null; 
try { 
    em = getEMF().createEntityManager(); 
    em.getTransaction().begin(); 
    em.persist(user); 

什么我需要改变，以获得此连接到MySQL？谢谢！

Answer 1

MySQL错误代码1049似乎是未知的数据库。

Error: 1049 SQLSTATE: 42000 (ER_BAD_DB_ERROR) 

Message: Unknown database '%s' 

https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html