I should modify where condition comes from one-to-many tag.

I'm using Hibernate2 and i'm a newby

in hbm file I have:

<class name="...">

<set name="test" cascade="all" lazy="false">
<key name="PK_USER"/>
<one-to-many class="MyClass"/>

The query derived have the follwing where condition
where PK_USER=?

I'd like modify in
where upper(PK_USER)=upper(?)

can anyone help me?

Thanks