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copied!<p>You have a many-to-many relationship between your songs and keywords.<br> I believe your query should be <code>select p from Playlist p, Songs s where p.user = :user and s.keywords member of p.keywords</code> although I'm not 100% sure you can do a <code>member of</code> operation between two collections. You might have to use a subquery to grab all the <code>p.keywords</code> and the <code>ANY</code> expression to do that. See <a href="http://download.oracle.com/docs/cd/E11035_01/kodo41/full/html/ejb3_langref.html#ejb3_langref_collection_member" rel="nofollow noreferrer">this article</a> for more.</p> <p>After your answer, I realized that a playlist was not the list of songs you're getting from the JPQL. You're trying to get a field set in the playlist object.</p> <p>If you're thinking that JPA is just an easy way to do DB work. You're sorta right. You can't really do what I believe your doing in any OO language. You can't define a field as the result of a query.</p> <p>What you can do, however is get the playlist definition from the user, name, and keywords that are part of the playlist. Then run a query looking for songs with those keywords, and then in java do something like <code>curPlaylist.addAll( queryResult); em.merge(curPlaylist);</code>. This assumes that you have your cascades set right of course. Now, when you get the playlist from the entity manager, you'll also pull back the playlist. </p> <p>If your looking for something more dynamic, where the list is automatically updated, then you can run the query every time you need a list matching the playlist criteria.</p>

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