joined-subclass and IDENTITY_INSERT

tortenegger · **Joined:** Wed Jun 16, 2004 8:26 am **Posts:** 19

Hi all,

i try to insert into a joined-subclass table on MS-SQL-Server with identifiers of type 'identity' .

Mapping

Code:

<hibernate-mapping>
    <class name="com.tecdoc.db_update.hibernate.Bean_Update_Installation" 
        table="t_Update_Installation">
        <id unsaved-value="0" name="idInstall" column="idInstall" 
            type="integer">
            <generator class="identity">
            </generator>
        </id>
        <property name="installDatum" column="installDatum" 
            type="java.lang.String"/>
        <property name="installVon" column="installVon" 
            type="java.lang.String"/>
        <property name="installBemerkung" column="installBemerkung" 
            type="java.lang.String"/>
        <many-to-one name="teilUpdate" 
            class="com.tecdoc.db_update.hibernate.Bean_Update" not-null="true"/>

    <joined-subclass name="com.tecdoc.db_update.hibernate.Bean_Datenbank" 
        table="t_Datenbank">
        <key column="idDb"/>
        <many-to-one name="server" 
            class="com.tecdoc.db_update.hibernate.Bean_Server" not-null="true"/>
        <many-to-one name="sid" class="com.tecdoc.db_update.hibernate.Bean_SID" 
            not-null="true"/>
    </joined-subclass>

    <joined-subclass         name="com.tecdoc.db_update.hibernate.Bean_Applikation" 
        table="t_Applikation">
        <key column="idApplikation"/>
        <many-to-one name="app" 
            class="com.tecdoc.db_update.hibernate.Bean_App" 
            not-null="true"/>
    </joined-subclass>
    </class>

</hibernate-mapping>

when i call saveOrUpdate i get the following error:
[code]
Caused by: java.sql.SQLException: Ein expliziter Wert f

michael · **Posted:** Mon Jul 19, 2004 4:53 am

the key column of a joined-subclass table can not be autogenerated by the database, which is quite clear if you think about it. Only the main class table id may be autogenerated.

tortenegger · **Joined:** Wed Jun 16, 2004 8:26 am **Posts:** 19

Thanks i forgot to change this to the create_table-script of my DB.

brianstclair · **Joined:** Thu Nov 04, 2004 12:52 am **Posts:** 4

Given an object hierarchy where ThirdObject extends SecondObject which extends FirstObject, is the following schema for a table-per-subclass hierarchy ok?

Table 1

Code:

FirstObjects
------------
firstObjectId (PK, IDENTITY)
propertyOfFirstObject

Table 2

Code:

SecondObjects
-------------
secondObjectId (PK, IDENTITY)
firstObjectId (FK)
propertyOfSecondObject

Table 3

Code:

ThirdObjects
------------
thirdObjectId (PK, IDENTITY)
secondObjectId (FK)
propertyOfThirdObject

The table for each subclass has its own primary key which is an MS SQL Server IDENTITY column. Further, each subclass's table has a FK column which relates to the PK column of the parent class's table (FK secondObjectId in table ThirdObjects relates to PK secondObjectId in table SecondObjects, and so on). So again, is this schema correct for table-per-subclass hierarchy?

Second question, with regards to the PK columns in each subclass table, should they be included in the mapping for each subclass or not? Is the following mapping correct?

Code:

<class name="FirstObject" table="FirstObjects">
    <id name="firstObjectId" type="long">
        <generator class="native"/>
    </id>
    <property name="propertyOfFirstObject"/>
    <joined-subclass name="SecondObject" table="SecondObjects">
        <key column="firstObjectId"/>
        <property name="propertyOfSecondObject"/>
        <joined-subclass name="ThirdObject" table="ThirdObjects">
            <key column="secondObjectId"/>
            <property name="propertyOfThirdObject"/>
        </joined-subclass>
    </joined-subclass>
</class>

Is it correct that the PK columns for the subclasses are omitted from the mapping document entirely? Should they be in there with insert="false" and update="false"? Should they be in there as ids as with the parent class?

Hope the above was clear. Thanks, greatly, in advance, and kudos on a phenomenal tool!

Brian St.Clair