More than one row with the given identifier was found

ruuit · **Posted:** Sun Jun 13, 2004 11:19 am

Hello forum,

I have a problem with an inheritance mapping. I'm using hibernate version 2.1.4, mysql 4.1 alpha and mysql-connector 3.1.1 alpha.

I prepared a simple mapping file that produces a HibernateException with the message below when I try to load an instance of class test.hibernate.inherit.Child from the database. The exception is thrown whenever there is more than one row in the child table.

Code:

"More than one row with the given identifier was found: 4, for class: test.hibernate.inherit.Child

This is the mapping file:

Code:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 2.0//EN" 
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
    <class
        name="test.hibernate.inherit.Parent"
        table="test_hibernate_inherit_parent"
        dynamic-update="false"
        dynamic-insert="false"
    >

        <id
            name="id"
            column="id"
            type="java.lang.Long"
        >
            <generator class="native">
            </generator>
        </id>

        <property
            name="name"
            type="java.lang.String"
            update="true"
            insert="true"
            access="property"
            column="name"
        />

        <joined-subclass
            name="test.hibernate.inherit.Child"
            table="test_hibernate_inherit_child"
            dynamic-update="false"
            dynamic-insert="false"
        >
        <key
            column="id"
        />

        </joined-subclass>

    </class>

</hibernate-mapping>

Thanks for any help,

ruuit

gavin · **Posted:** Sun Jun 13, 2004 1:00 pm

Quote:

The exception is thrown whenever there is more than one row in the child table.

The id property is intended to be the primary key, or at least a unique key, of the database table.

ruuit · **Posted:** Sun Jun 13, 2004 3:21 pm

Quote:

The id property is intended to be the primary key, or at least a unique key, of the database table.

Yes, but I think in the mapping id is not defined as a usual property but as a primary key column for the table. The native generator class should provide unique primary key and the contents of the id column in the table are unique, indeed. I hope the mapping is defined correctly?

emmanuel · **Posted:** Mon Jun 14, 2004 12:57 pm

Set you DB column as a real PK, it won't ahppen again

ruuit · **Posted:** Mon Jun 14, 2004 1:40 pm

emmanuel wrote:

Set you DB column as a real PK, it won't ahppen again

Thanks for your reply Emmanuel.

Could you please be a little more specific? What do you mean by "real PK"? Is there something missing in the mapping file?

I use schema export for database creation and these are the create statements:

Code:

create table de_ruu_test_hibernate_inherit_child (
   id BIGINT not null,
   primary key (id)
) type=InnoDB;
create table de_ruu_test_hibernate_inherit_parent (
   id BIGINT NOT NULL AUTO_INCREMENT,
   name VARCHAR(255),
   primary key (id)
) type=InnoDB;

Is there anything wrong with that? BTW: mysql and other tools report existing primary keys for the tables.

emmanuel · **Posted:** Mon Jun 14, 2004 6:07 pm

Hum, I don't uderstand
Do you have more than one row with ID=4, in de_ruu_test_hibernate_inherit_child ?
There should not

ruuit · **Posted:** Mon Jun 14, 2004 11:33 pm

emmanuel wrote:

Hum, I don't uderstand
Do you have more than one row with ID=4, in de_ruu_test_hibernate_inherit_child ?
There should not

No, I'm sure there is only one row in the child table, but of course there is one row with the same id in the parent table. I think this is how inheritance is meant to work, isn't it?

emmanuel · **Posted:** Mon Jun 21, 2004 3:11 am

ruuit wrote:

emmanuel wrote:

there is one row with the same id in the parent table. I think this is how inheritance is meant to work, isn't it?

Correct if you use joined-table.
But if you have Parent <- ChildType1 and Parent <- ChildType2
An id has to be on Child1 or Child2 not both

ruuit · **Posted:** Mon Jun 21, 2004 4:21 am

Emmanuel,

thanks for your help. During weekend I managed to solve the problem. I traced mysql, found some strange output, did a little google investigation and found a hint that made me downgrade the mysql db to a stable (not alpha development) version. From there on this and other errors disappeared.

Thanks again!