"Unknown database 'mydb' " error with jpa

i'm trying to connect to mysql server but get this error. when mydb is the only name in the system. please tell me where i'm wrong...

my persistence xml is as folow:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
 version="1.0">

 <persistence-unit name="MyPersistenceUnit">

  <provider>org.hibernate.ejb.HibernatePersistence</provider>

  <properties>
   <property name="hibernate.archive.autodetection" value="class" />
   <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
   <property name="hibernate.connection.url" value="jdbc:mysql://localhost:开发者_如何学C3306/mydb" />
   <property name="hibernate.connection.username" value="root" />
   <property name="hibernate.connection.password" value="tft" />
   <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />

   <property name="hibernate.hbm2ddl.auto" value="create" />

   <property name="hibernate.show_sql" value="true" />
   <property name="hibernate.format_sql" value="true" />
   <property name="hibernate.use_sql_comments" value="true" />
  </properties>

 </persistence-unit>
</persistence>

1.You have to check your mysql jdbc driver

2.You have to check mysql server state and validation of username & password.