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Select Bean with unique property using Criteria

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IvanLatysh

Post subject: Select Bean with unique property using Criteria

Posted: Fri Mar 03, 2006 4:30 pm

Beginner

Joined: Thu Jul 08, 2004 2:21 pm
Posts: 20
Location: Toronto

I am trying to express the following query using Criteria :

Code:

from Cat as cat group by cat.name

So simply select all cat's with unique name.

And no luck so far.

Code:

Criteria cr = session.createCriteria(Cat.class);
cr.setProjection(Projections.groupProperty("name"));

Will return only names, when I need the whole Cat.

I think that I am missing something, it look like a trivial task to me.

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tenwit

Post subject:

Posted: Sun Mar 05, 2006 7:10 pm

Expert

Joined: Thu Dec 23, 2004 9:08 pm
Posts: 2008

Group isn't the same as distinct. If you "select * from cat group by name" in SQL, you'll get an error. You could "select name from cat group by name", or "select sum(age) from cat group by name", but you can't do what you're trying to do.

You want "from cat c where (select count(*) from cat group by name) = 1". If you can't get the criteria for that working, post again and I'll work it out for you. (Hint: subqueries are done using DetachedCriteria)

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tenwit

Post subject:

Posted: Sun Mar 05, 2006 7:16 pm

Expert

Joined: Thu Dec 23, 2004 9:08 pm
Posts: 2008

Oops. Obviously I meant "from cat c where c.name = (select count(c2.*) from cat c2 where c2.name = c.name) = 1"

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