kab wrote:
> Hi,
>
> I tried to directly insert a Java object from typ mottrow.MItem to the
> table ITEMS in my embedded Derby DB. But I got the following error:
>
> java.sql.SQLException: An attempt was made to get a data value of type
> 'BLOB' from a data value of type ' mottrow.MItem'
>
> In the query I used, I had defined the row ITEM to the typ BLOB, because
> with the typ JAVA_OBJECT I got an error. In the derby documentation I
> have read that the a JAVA_OBJECT is stored as BLOB in the DB, so I
> defined it directly as BLOB.
>
> SQL query used to create table:
>
> String query = "create table APP.ITEMS (" +
> "ID INT NOT NULL PRIMARY KEY GENERATED ALWAYS AS
> IDENTITY (START WITH 1, INCREMENT BY 1)," +
> "ITEM BLOB," +
> "LEVEL INT NOT NULL," +
> "OWNER VARCHAR(30)," +
> "LASTACCESS DATE," +
> "FORMERLEVEL INTEGER NOT NULL )";
>
> Statement to insert my JAVA_OBJECT:
>
> PreparedStatement stmt = con.prepareStatement("insert into
> APP.ITEMS (ITEM) VALUES (?)");
> stmt.setObject(1,item);
> stmt.addBatch ( );
>
> Does somebody knows a solution for this problem?
Hello Kevin,
I'm sure someone will give you the full story, but I believe you might
have to serialize your objects yourself before you store them into the
database as BLOB/VARCHAR FOR BIT DATA (depending on the maximum size of
your objects, or your own preferences).
Another way to go is to use the object relational mapping technique, a
third is to use an object-store instead of a relational database.
I think the JAVA_OBJECT type in Derby has been disabled, but could it
have been available in earlier Cloudscape releases?
I see comments in the code suggesting the support for JAVA_OBJECT is
"half-baked", so it would be nice if someone with knowledge of earlier
times could enlighten the rest of us :)
regards,
--
Kristian
>
>
> Sincerely
>
> Kevin
>
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