如题 数据库中有Student Course和Score三张表 Score是连接表
三张表分别都有ID字段为主键 使用@GeneratedValue自动生成ID
但是Score只要使用@GeneratedValue存储就会报错 提示Caused by: java.sql.SQLException: Field 'id' doesn't have a default value 需要初始值
不设ID自动生成存储没问题
求大神帮忙指点一下 谢谢 谢谢
错误信息如下org.hibernate.exception.GenericJDBCException: could not insert: [com.hibernate.dao.Score]
        at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:63)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2346)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2853)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:320)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129)
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:713)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:701)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:697)
at com.hibernate.dao.HibernateTreeTest.testSave1(HibernateTreeTest.java:68)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:46)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:43)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:270)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:62)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:52)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
at org.junit.runners.ParentRunner.run(ParentRunner.java:307)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
Caused by: java.sql.SQLException: Field 'id' doesn't have a default value
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4074)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4006)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2468)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2629)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2719)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2450)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2371)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2355)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:93)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:56)
... 41 more实体类如下
Scorepackage com.hibernate.dao;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;@Entity
@Table(name="score")
public class Score {
private int id;
private int score;
private Student student;
private Course course;

@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}

public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
@ManyToOne
@JoinColumn(name="student_id")
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}

@ManyToOne
@JoinColumn(name="course_id")
public Course getCourse() {
return course;
}
public void setCourse(Course course) {
this.course = course;
}
}Student
package com.hibernate.dao;import java.util.HashSet;
import java.util.Set;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;@Entity
public class Student {
private int id;
private String name;
private Set<Course> courses = new HashSet<Course>();

@ManyToMany
@JoinTable(name="score",
joinColumns=@JoinColumn(name="student_id", referencedColumnName="id"),
inverseJoinColumns=@JoinColumn(name="course_id", referencedColumnName="id")
)
public Set<Course> getCourses() {
return courses;
}
public void setCourses(Set<Course> courses) {
this.courses = courses;
}
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}Coursepackage com.hibernate.dao;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;@Entity
public class Course {
private int id;
private String name;
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}

}配置信息如下<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"><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/hibernate</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.MySQL5Dialect</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.hibernate.dao.Student"/>
<mapping class="com.hibernate.dao.Course"/>
<mapping class="com.hibernate.dao.Score"/> </session-factory></hibernate-configuration>

解决方案 »

  1.   

    我以前也有用过多对多的关系,但主要是写的是双主键上,中间表不需要维护。但看你这样写了后,为什么不用OneToMany/ManyToOne呢?如果用这个,就不会存在问题了。
      

  2.   

    这段信息需要修改过。at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:63)为
    at www.bc888.com org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2346)
      

  3.   

    改成这样试试。。
    @Entity
    @Table(name="score")
    public class Score {
    private int id;
    private int score;
    private Student student;
    private Course course;@Id
    @GeneratedValue(strategy=GenerationType.IDENTITY )
    public int getId() {
    return id;
    }
      

  4.   


    谢谢 谢谢 选strategy=GenerationType.IDENTITY的ID生成策略就好了