How to create two-column unique key constrain with HBM mapping?

I have a hibernate mapping:

<properties name="lrt_bps_bpr_acs_uk" unique="true">
    <many-to-one name="activitySummary" column="bps_acs_id" class="xyz.ActivitySummary"
    unique-key="lrt_bps_bpr_acs_uk"/>
    <many-to-one name="bestPractice" column="bps_bpr_id" class="xyz.BestPractice" 
        unique-key="lrt_bps_bpr_acs_uk"/>
</properties>

I expected that hibernate would开发者_开发百科 create unique constraint on database for this mapping. Nothing like that happened however.

What am I doing wrong?

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Seems like you do nothing wrong. We do it the same way in our project and it works fine. I thought to have the same problem once because I couldn't find the constaints in our oracle DB because I thought the specified unique-key attribute value (in your case 'lrt_bps_bpr_acs_uk') is used as constraint_name in the DB. But that isn't the case (at least with oracle DB).

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What's the actual DDL that Hibernate is generating? What would be the DDL if you remove the unique-key parameters? What's the Hibernate version?

From the documentation, it seems you are doing it correctly: http://docs.jboss.org/hibernate/core/3.3/reference/en/html/mapping.html#mapping-declaration-properties

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Dont specify name="lrt_bps_bpr_acs_uk" unique="true" in the properties element. It automatically takes it and applies the constraint with unique-key