Read from 2 tables, write only to one. Simple, but impossible??

Question

I've been messing about with various annotations for quite a while now, and I can't seem to figure out how to accomplish this seemingly simple task. I'm hoping somebody could explain to me the probably very obvious and simple mistake that I am making.
I realize that question would otherwise point to problems in my database design and persistence strategy, but I can't seem to read from 2 tables, and write to only one. I have an entity bean that refers mainly to one table, but needs just one column of information from another table. It should not attempt to alter the secondary table, just join on it to get the one field it needs. So far, I've got the following:
@Entity
@Table(name = "ventureprofile")
@SecondaryTable(name = "venture",
                pkJoinColumns = @PrimaryKeyJoinColumn(name="ventureid"))
@NamedQueries( {
        @NamedQuery(name = "Ventureprofile.findByVentureprofileid", query = "SELECT v FROM Ventureprofile v WHERE v.ventureprofileid = :ventureprofileid"),
        @NamedQuery(name = "Ventureprofile.findByVentureid", query = "SELECT v FROM Ventureprofile v WHERE v.ventureid = :ventureid"),
        @NamedQuery(name = "Ventureprofile.findByVenturesummary", query = "SELECT v FROM Ventureprofile v WHERE v.venturesummary = :venturesummary"),
        @NamedQuery(name = "Ventureprofile.findByLogoimagelocation", query = "SELECT v FROM Ventureprofile v WHERE v.logoimagelocation = :logoimagelocation"),
        @NamedQuery(name = "Ventureprofile.findByVisible", query = "SELECT v FROM Ventureprofile v WHERE v.visible = :visible ORDER BY v.venturename")
public class Ventureprofile implements Serializable {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO, generator="Ventureprofile.ventureprofileid.seq")
    @SequenceGenerator(name="Ventureprofile.ventureprofileid.seq", sequenceName="ventureprofile_ventureprofileid_seq", allocationSize=1) 
    @Column(name = "ventureprofileid", nullable = false)
    private BigInteger ventureprofileid;      
    @Column(name = "ventureid", table="ventureprofile", nullable = false)
    private Long ventureid;
    @Column(name = "venturesummary")
    private String venturesummary;
    @Column(name = "logoimagelocation")
    private String logoimagelocation;
    @Column(name = "visible", nullable = false)
    private boolean visible;  
    @Column(table = "venture", name = "venturename", nullable=false, insertable=false, updatable=false)
    private String venturename;
//... The extra column of data is "venturename", the tables are related by the column "ventureid". I contest, that since I have specified for read/write access no fields mapped to the 'venture' table (I specified with 'table=' any ambiguous columns), and described the table relationship via my @PrimaryKeyJoinColumn annotation, that toplink should not try to persist anything to the 'venture' table. However, I am getting the following exception:
Exception [TOPLINK-4002] (Oracle TopLink Essentials - 2.0 (Build b58g-fcs (09/07/2007))): oracle.toplink.essentials.exceptions.DatabaseException
Internal Exception: org.postgresql.util.PSQLException: ERROR: null value in column "venturename" violates not-null constraint
Error Code: 0
Call: INSERT INTO venture (ventureid) VALUES (?)
        bind => [220]
Query: InsertObjectQuery(VCMarkWeb.db.entity.Ventureprofile[ventureprofileid=220])
        at oracle.toplink.essentials.exceptions.DatabaseException.sqlException(DatabaseException.java:311)
...It seems pretty clear that toplink is trying to insert an empty row into the secondary table, and barfing since it is inserting no values, including those constrained to be nonnull. Anyway...I hope it's clear what's going on here, and perhaps somebody knows the right way to do this. Thanks fot your help!

Answer 1

Tom and Cornelius,
Thank you both for your ideas. This what I think I will do:
1) Drive up to OWC (fortunately they are only about 15 miles away from where I live) and get a bigger HD and some more RAM.
2) Copy the OS9 applications on the existing HD to a thumb drive.
3) Install the new hard drive and memory
4) Install OSX TIger and 9.2.2
5) Maybe do the 4.1.8 firmware update also, maybe.
6) Look around for a Superdrive and if I can get one for a good price, I'll do it otherwise I'll just use USB thumb drives if I need to copy something off the PB.
One thing that I was fighting with the other day was that when I had the yoyo power supply plugged in and attached when the PB was in the kitchen, the batteries would not charge although the yoyo was outputting +24 VDC.
I move everything to the garage, where I originally fixed the yoyo power supply, plug it in out there and the batteries started charging!!! Scratching my head...then I check the voltage between the metal barrel (with the Vsensing resistor attached between the metal shell and the ground wire) of power supply plug and the +24 VDC wire and there is 22 to 23 VDC with the batteries being charged. In the kitchen when they were not being charged, it was about 1.0 VDC. So I rotate the plug a little bit and the batteries start charging. Rotate it more and the batteries don't charge. Something else to do when I have spare time.
Anyway, thanks for the help and suggestions.
John