hibernate4.x自动建表时候创建外键失败ERROR: HHH000389: Unsuccessful: alter table ORDERS_NOPK1 add index

1 错误描述：

场景：hibernate 自动建立非主键多对一关联时候

ERROR: HHH000389: Unsuccessful: alter table ORDERS_NOPK1 add index FK_590egrftni5wpw63w6fcc1atx (CUSTOMER_ID), add constraint FK_590egrftni5wpw63w6fcc1atx foreign key (CUSTOMER_ID) references CUSTOMERS_NOPK1 (cy_id)
ERROR: Cannot add foreign key constraint

Customer.java

package cn.com.pojo.n21.both.notPK;

import java.util.HashSet;
import java.util.Set;

public class Customer {

    private Integer id;
    // 外键对应列
    private Integer cyId;
    private String customerName;
    private Set orders = new HashSet<>();
    public Customer() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getCustomerName() {
        return customerName;
    }
    public void setCustomerName(String customerName) {
        this.customerName = customerName;
    }
    public Set getOrders() {
        return orders;
    }
    public void setOrders(Set orders) {
        this.orders = orders;
    }
    public Integer getCyId() {
        return cyId;
    }
    public void setCyId(Integer cyId) {
        this.cyId = cyId;
    }
    @Override
    public String toString() {
        return "Customer [id=" + id + ", cyId=" + cyId + ", customerName="
                + customerName + ", orders=" + orders + "]";
    }
}

Customer.hbm.xml

<hibernate-mapping package="cn.com.pojo.n21.both.notPK">
    <class name="Customer" table="CUSTOMERS_NOPK1">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="native" />
        id>
        <property name="customerName" type="java.lang.String">
            <column name="CUSTOMER_NAME" />
        property>

        <property name="cyId" type="java.lang.Integer">
            
            <column name="cy_id"/>  
        property>

        
        <set name="orders" table="ORDERS"  cascade="delete" inverse="true">
            
            <key column="CUSTOMER_ID" property-ref="cyId">key>
            
            <one-to-many class="Order"/>
        set>
    class>
hibernate-mapping>

Order.java

package cn.com.pojo.n21.both.notPK;

public class Order {

    private Integer orderId;
    private String orderName;

    private Customer customer;

    public Order() {
        super();
        // TODO Auto-generated constructor stub
    }



    @Override
    public String toString() {
        return "Order [orderId=" + orderId + ", orderName=" + orderName
                +  "]";
    }


    public Integer getOrderId() {
        return orderId;
    }

    public void setOrderId(Integer orderId) {
        this.orderId = orderId;
    }

    public String getOrderName() {
        return orderName;
    }

    public void setOrderName(String orderName) {
        this.orderName = orderName;
    }

    public Customer getCustomer() {
        return customer;
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
}

Order.hbm.xml

<hibernate-mapping package="cn.com.pojo.n21.both.notPK">
    <class name="Order" table="ORDERS_NOPK1">

        <id name="orderId" type="java.lang.Integer">
            <column name="ORDER_ID" />
            <generator class="native" />
        id>

        <property name="orderName" type="java.lang.String">
            <column name="ORDER_NAME" />
        property>
          
         <many-to-one name="customer" class="Customer" property-ref="cyId">
            <column name="CUSTOMER_ID"/>  
         many-to-one>

    class>
hibernate-mapping>

2 分析原因：

原因可能出现在外键与其对应字段不符合上面
2.1来源于网络：
（1）外键对应的字段数据类型不一致
排除： show create table table_name

（2）两张表的存储引擎不一致
排除： show table status from db_name where name=’table_name’;

（3）设置外键时“删除时”设置为“SET NULL”
排除：

2.2补充：以上原因在这种情况下不太可能出现，因为都是hibernate自动建表，此时可能是下面原因
（4）外键对应字段必须设置 非空并且唯一

3 解决问题：

发现外键对应列没有设置非空或者唯一约束，应该加上约束条件

<property name="cyId" type="java.lang.Integer">
   "cy_id" not-null="true" unique="true"/>
property>