例子：
Post p = new Post();
p.setPostId(3);
p.setPostName("技术");
在执行数据保持时提示session.save(p); 的错误。
INFO: HHH000232: Schema update complete
Hibernate: insert into Post (postName) values (?)
八月 19, 2018 5:07:17 下午 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
WARN: SQL Error: 1364, SQLState: HY000
八月 19, 2018 5:07:17 下午 org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: Field 'PostId' doesn't have a default value
Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not execute statement
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:190)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3558)
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:97)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:488)
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:193)
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:177)
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:212)
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:324)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:288)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
控制台出现的错误
解决问题步骤：
- 查看Post.hbm.xml 文件
<class name="hibernate.model.Post" table="Post">
<id name="postId">
<!-- 主键生成策略 -->
<generator class="native"></generator>
</id>
<property name="postName"/>
2. <!-- 主键生成策略 -->
<generator class="native"></generator>
3. 删掉。
4. 重新运行。
原因：
Post.hbm,xml配置文件里的<generator class="native"></generator>对主键已经默认赋值了，在Post.java里在插入语句，造成冲突，所以出错。