For some reason when i run my createQuery from the Session object that is initialized, it returns the correct number of objects, but the objects are duplicated. It seems that hibernate pulls the first row it finds containing my first column value.

Example:

DB Table

ROW_1 ROW_2 ROW_3 ROW_4
1234 abcd 10-08-2008 dev
1234 efgh 11-08-2008 dev
1234 ijkl 12-08-2008 dev
1234 mnop 1-08-2009 dev

if this were the data contained in my table and i had an HQL like this:

String SQL_STRING = "FROM UnitData data WHERE data.row4 = '" + row4 + "' ORDER BY data.row1 asc";

I would get 4 UnitData objects all with the same data:
1234 abcd 10-08-2008 dev

Any ideas as to why that happens?

What is your mapping for the UnitData class? Have you mapped an <id> property and how? From the table data you I can't see any column that seems like a primary key.

I have mapped my <id> propery - below is the mapping.

<hibernate-mapping>
<class name="UnitData" table="ONESITE_UNIT">
<id column="ROW_1" name="row1" />

<property column="ROW_2" name="row2" />
<property column="ROW_3" name="row3" />
<property column="ROW_4" name="row4" />
</class>
</hibernate-mapping>

use distinct:


Christophe

I tried using distinct in my HQL string, but that did not correct my problem either.

The problem is that you have mapped ROW_1 as <id> when in fact there is more than one row that has the same value. The column used for the <id> attribute should be the primary key of the table or at least have a unique value for each row. If there is no such column in the table you may have to use a composite id that consists of as many column that you need to make up a unique value. Read more about this here: http://www.hibernate.org/hib_docs/v3/re ... ompositeid

This doesn't really answer your original question (why you get 4 objects with the same data), so I'll try to do that as well. Hibernate uses the value of the <id> property to store all loaded objects in an internal cache (the first-level cache). So, the first row is read, a UnitData object is created, stored in the cache, and then returned as a query result. When the second row is about to be read Hibernate first reads the ROW_1 value. Hibernate checks the cache and finds that there is already a UnitData object for that value. Since the cache can only contain a single object for each <id> value Hibernate simply returns the object that is stored in the cache and never reads the remaining columns from the database. The same happens for the remaining rows.

Thanks for your help!! That solved my problem.