Hibernate：alter table User_Address drop外键FK_im39k3og2pvx7vvqdcy35s0g0

Question

当我首先运行我的代码时它工作正常，但后来我无法访问它们 表？

这是我的代码： -

的hibernate.cfg.xml

<hibernate-configuration>

    <session-factory>

        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/navlic</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>


         <!-- Drop and re-create the database schema on startup -->
         <property name="hbm2ddl.auto">create</property>          

        <mapping class="dto.UserDetails"/>

    </session-factory>

</hibernate-configuration>

主要课程： -

package dto;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.GenerationType;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.annotations.CollectionId;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Type;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateTest {

    public static void main(String[] args) {
        UserDetails ud=new UserDetails();
        ud.setUserName("Second user");


        Address homead=new Address();
        homead.setCity("smg");
        homead.setCountry("aa");
        homead.setHouse("bb");
        homead.setStreet("cc");
        homead.setState("dd");


        Address officead=new Address();
        officead.setCity("smg");
        officead.setCountry("ee");
        officead.setHouse("ff");
        officead.setStreet("gg");
        officead.setState("hh");


        ud.getAddr().add(homead);
        ud.getAddr().add(officead);


            SessionFactory sf;
            ServiceRegistry sr;
            Configuration cfg=new Configuration().configure();
            sr=new StandardServiceRegistryBuilder().applySettings(cfg.getProperties()).build();
            sf=cfg.buildSessionFactory(sr);


        Session s=sf.openSession();
        s.beginTransaction();
        s.save(ud);
        s.getTransaction().commit();
        s.close();

        ud=null;
        s=sf.openSession();
        //if type is lazy it returns only the variables of that class no more reference variables.
        //if type is Eager it returns all the elements of user class
        ud=(UserDetails)s.get(UserDetails.class, 1);
        System.out.println(ud.getAddr().size());


    }

}

模特课： -

@Entity
public class UserDetails {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int UserId;
    private String UserName;



    @ElementCollection(fetch=FetchType.EAGER)
    @JoinTable(name="User_Address",joinColumns=@JoinColumn(name="User_Id"))
    @GenericGenerator(name="hilo-gen" ,strategy="hilo")
    @CollectionId(columns={@Column(name="AddressId")},generator="hilo-gen",type=@Type(type="long"))
    private Collection<Address> addr=new ArrayList<Address>();


    public Collection<Address> getAddr() {
        return addr;
    }
    public void setAddr(Collection<Address> addr) {
        this.addr = addr;
    }
    public int getUserId() {
        return UserId;
    }
    public void setUserId(int userId) {
        UserId = userId;
    }
    public String getUserName() {
        return UserName;
    }
    public void setUserName(String userName) {
        UserName = userName;
    }

}

地址类在这里： -

@Embeddable
public class Address {
    @Column(name="Office_name")
    private String House;
    public String getHouse() {
        return House;
    }
    public void setHouse(String house) {
        House = house;
    }
    public String getStreet() {
        return Street;
    }
    public void setStreet(String street) {
        Street = street;
    }
    public String getCity() {
        return City;
    }
    public void setCity(String city) {
        City = city;
    }
    public String getState() {
        return State;
    }
    public void setState(String state) {
        State = state;
    }
    public String getCountry() {
        return Country;
    }
    public void setCountry(String country) {
        Country = country;
    }
    @Column(name="street_name")
    private String Street;
    @Column(name="city_name")
    private String City;
    @Column(name="state_name")
    private String State;
    @Column(name="country_name")
    private String Country;


}

当我尝试运行我的代码时没有来自hibernate的错误但是遇到了mysql错误我是mysql的新手可以任何人解释我这个错误的原因以及如何解决它。

提前致谢