org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.

今天报了这个异常，这是页面报的

org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.

控制台报 

18:52:35,859 ERROR SqlExceptionHelper:147 - Cannot delete or update a parent row: a foreign key constraint fails (`zl_cms`.`t_channel`, CONSTRAINT `FK_8xberajm2i2c97rwrellh0eqk` FOREIGN KEY (`pid`) REFERENCES `t_channel` (`id`)

channel对象自关联

<hibernate-mapping package="com.zl.cms.model">
<class name="Channel" table="t_channel">
<id name="id">
<generator class="identity"/>
</id>
<property name="name" type="string"/>
<property name="customLink" type="int" column="custom_link"/>
<property name="customLinkUrl" type="string" column="custom_link_url"/>
<property name="index" type="int" column="is_index"/>
<property name="topNav" type="int" column="is_top"/>
<property name="status" type="int"/>
<property name="recommed" type="int"/>
<property name="orders" type="int"/>
<many-to-one name="parent" column="pid" cascade="all" class="Channel"/>
<property name="type">
<type name="org.hibernate.type.EnumType">
<param name="enumClass">com.zl.cms.model.ChannelType</param>
<param name="type">4</param>
</type>
</property>
</class>
</hibernate-mapping>

原因是 hibernate级联删除问题。

   <many-to-one name="parent" column="pid" cascade="all" class="Channel"/> 这里设置了all ，应该设置成none不进行级联操作

，这个和数据库还是有区别

 数据库外键检查。一般情况是，当你删除父键时，不让删除，因为有子键引用这个父建id，但是hibernate的级联不一样。删除子键也不行 ,所以取消级联