I am writing a hibernate wrapper around a client's database. This one particular table does not have a primary key.

This is the SQL that created the table

CREATE TABLE [CONFIG] (
[Name] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,
[Value] [varchar] (50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,
[LastModified] [datetime] NULL
) ON [PRIMARY]
GO

I used Middlegen to create my mapping file and this is what it come up with...

<?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>
<!--
Created by the Middlegen Hibernate plugin 2.1

http://boss.bekk.no/boss/middlegen/
http://www.hibernate.org/
-->

<class
name="com.unveil.bizobjs.lecstar.hibernate.Config"
table="CONFIG"
>

<composite-id>
<key-property
name="name"
column="Name"
type="java.lang.String"
length="50"
/>
<key-property
name="value"
column="Value"
type="java.lang.String"
length="50"
/>
<key-property
name="lastModified"
column="LastModified"
type="java.sql.Timestamp"
length="23"
/>
</composite-id>


<!-- Associations -->
<!-- derived association(s) for compound key -->
<!-- end of derived association(s) -->


</class>
</hibernate-mapping>

Middlegen has automatically created a composite primary key comprised of every row in the table.

After much debugging and searching I have discovered that Hibernate won't allow me to update the fields in a composite primary key.

So you may ask why don't I add an ID column to the table. Well, the schema is not really up for change. I need to make it work witht he existing one.

You may also ask how I can select a for update when there is no primary key. Glad you asked. My client has given me this query statement that select's the row that needs to be updated...

Query query = session.createSQLQuery("select top 1 {config.*} from Config config where config.name like 'CreditcardUser%' and (DateDiff(\"n\", config.lastModified, getdate()) >= 3 or config.value = '') and config.value <> 'PCCHARGE'", "config", Config.class);

Apparently this selects a row unique enough for their needs

So my question is what can I do to update one of these rows?

I'm using Hibernate 2.1 with SQL Server 2000 sp3a

To answer your question logically, you have to override the hashCode() and equals() method in you class, by putting the bussiness logic, i mean the composite id's that you will be having.

To find the record, you should execute a named query specifying all the values for each of the composite-keys.

Ideally you should have a seperate class which represents the composite-key.

Is this the same as a "synthetic key" that I have read about in the book "Hibernate in Action?" If so do you know where I can find more documentation on synthetic keys? That book doesn't go into much detail.

Thanks