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From Marc Prud'hommeaux <mprud...@apache.org>
Subject Re: Getting a group of entities by ID
Date Wed, 18 Jul 2007 18:47:15 GMT
Christian-

Glad it works. Note that it is debatable that the spec actually  
allows this. Technically, an IN clause is supposed to be of the form  
(ob1, ob2, ob3), and the spec doesn't say anything about allowing  
Collections to be used as parameters to an IN clause. However, in my  
experience, all of the JPA implementations support passing in  
Collection parameters to IN clauses.



On Jul 18, 2007, at 11:43 AM, Christian Defoy wrote:

> Hi Marc,
>
> Thanks for the tip.  It works fine!  That's the functionality I was  
> looking for!
>
> I changed the query a bit because it looks like we have to enclose
> that specific parameter in ().
>    em.createQuery("SELECT x FROM shape x WHERE x.id in (:ids)");
>
> Thank you both for your time!
>
> Christian
>
> On 7/18/07, Marc Prud'hommeaux <mprudhom@apache.org> wrote:
>> Christian-
>>
>> In additional to what David said, I think should be able to do:
>>
>>    em.createQuery("SELECT x FROM shape x WHERE x.id in :ids").
>>       setParameter("ids", Arrays.asList(new Integer[] { 1, 2, 3 })).
>>       getResultlist();
>>
>>
>>
>>
>>
>>
>> On Jul 18, 2007, at 7:22 AM, David Ezzio wrote:
>>
>> > Hi Christian,
>> >
>> > You might consider using the OpenJPAEntityManager.findAll  
>> method.  The
>> > expected advantage is that any objects in the datacache won't  
>> cause a
>> > hit to the database.  If there is a high likelihood that all
>> > objects are
>> > in the datacache, then this is definitely the way to go.  If some
>> > objects will very likely not be in the cache, then you might  
>> want to
>> > investigate.  I'm not sure whether it will generate one SQL  
>> statement
>> > for all missing objects or one for each.  You might want to turn on
>> > SQL
>> > logging to check,
>> >
>> > ((OpenJPAEntityManager) em).findAll(...)
>> >
>> > Hope this helps,
>> >
>> > David
>> >
>> > Christian Defoy wrote:
>> >> Hello,
>> >>
>> >> I can't find an easy way of retrieving a group of entities by
>> >> specifying only their IDs. For example, if I want to get shapes  
>> with
>> >> IDs 1, 2, 4 and 6, do I have to do the following query or is  
>> there a
>> >> better way?
>> >>
>> >> SELECT x FROM shape x WHERE x.id = 1 OR x.id = 2 OR x.id = 4 OR
>> >> x.id = 6
>> >>
>> >> I was thinking of something more along the lines of the IN SQL
>> >> statement ("WHERE x.id IN (1,2,4,6)") but I haven't found  
>> anything to
>> >> do this.  Using SQL queries, I was able to retrieve my shapes but
>> >> OpenJPA does one select to retrieve the IDs (my SQL query with  
>> the IN
>> >> clause) and then one select per shape it retrieves.  That is no
>> >> different than me doing a find for every shape myself...
>> >>
>> >> Thanks in advance!
>> >>
>> >> Christian
>> >>
>> >
>> >
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>>


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