求教：Hibernate异常Could not execute JDBC batch update

配置文件为：

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<!-- 

    Mapping file autogenerated by MyEclipse Persistence Tools

-->

<hibernate-mapping>

    <class name="com.aisino.tree.entity.Personinfo" table="PERSONINFO">

        <id name="cid" type="string">

            <column name="CID" length="50" />

            <generator class="assigned" />

        </id>

        <property name="pid" type="string">

            <column name="PID" length="50" />

        </property>

        <property name="name" type="string">

            <column name="NAME" length="50" />

        </property>

        <property name="type" type="integer">

            <column name="TYPE"  />

        </property>

        <property name="isleaf" type="integer">

            <column name="ISLEAF"/>

        </property>

        <many-to-one name="parent">

            <column name="pid"/>

        </many-to-one>

        <set name="children" inverse="true" cascade="save-update">

            <key>

                <column name="pid"/>

            </key>

            <one-to-many class="com.aisino.tree.entity.Personinfo" />

        </set>

    </class>

</hibernate-mapping>

我想单独添加一条数据我就直接用session.save(Person);
然后系统给我报个错org.hibernate.exception.SQLGrammarException: Could not execute JDBC batch update。
发出的sql语句是：
Hibernate: insert into PERSONINFO (PID, NAME, TYPE, ISLEAF, pid, CID) values (?, ?, ?, ?, ?, ?)
就是pid出现重复列了，这是什么原因还是配置文件哪里有问题，好像它把parent对象也级联保存了，
但是我删除cascade配置也没用, 求教了。
(不知道大家看的懂这配置文件意思不，就是这样配置可以生成树的结构如：cid,pid)