Mailing-List: contact jdo-dev-help@db.apache.org; run by ezmlm
Precedence: bulk
Reply-To: jdo-dev@db.apache.org
Received-SPF: pass (nike.apache.org: local policy)
Date: Thu, 25 Oct 2007 09:03:43 -0700
From: Craig L Russell <Craig.Russell@Sun.COM>
Subject: Re: Subquery specification update
In-reply-to: <4720B83B.8040703@spree.de>
Sender: Craig.Russell@Sun.COM
To: jdo-dev@db.apache.org
Cc: JDO Expert Group <jdo-experts-ext@Sun.COM>
Message-id: <7FF16E30-FD64-4550-8B70-CC00A8D426F8@SUN.com>
MIME-version: 1.0
Content-type: multipart/signed; protocol="application/pkcs7-signature";
 boundary=Apple-Mail-113-272658962; micalg=sha1
References: <50746A9B-FB9E-4A91-818E-619BC806719D@Sun.COM>
 <13405438.post@talk.nabble.com>
 <F15C3D66-E9EF-47A5-8F67-DBD7E8FFD3B6@matthewadams.org>
 <4720B83B.8040703@spree.de>

--Apple-Mail-113-272658962
Content-Transfer-Encoding: 7bit
Content-Type: text/plain;
	charset=US-ASCII;
	delsp=yes;
	format=flowed

Currently, parameters are only specified to work in the result,  
filter, ordering, grouping, or range parts of a query, not in the  
FROM part.  This is in both the single string version (from  
CandidateClassName ExcludeClause opt) and API version where the  
setCandidates takes either Extent or Collection, not parameter name.

I'm not necessarily opposed to adding the ability to use parameters  
as the candidate collection, but I'd like to hear more details as to  
how a parameter can be used as a candidate collection, and from the  
implementation engineers to see if this change could be done.

The only problem I have with including single string JDOQL to the  
examples is that it would be before the single string JDOQL topic was  
introduced. Would it be better to move all the subquery examples down  
to the examples section?

Craig

On Oct 25, 2007, at 8:37 AM, Michael Bouschen wrote:

> Hi Matthew, hi Christiaan,
>> I agree that the candidateCollectionExpression description is a  
>> bit cryptic.
> Do you have an idea for a better description? The reason to include  
> something like "tokens from this query" is that we have to define  
> the scope for identifiers used in the  
> candidateCollectionExpression. So in "this.department.employees"  
> this denotes the candidate instance of the outer query and NOT of  
> the subquery.
>>
>> Boy, it's been a long time since I thought about subqueries.  Can  
>> we also provide single-string versions of the examples?  That  
>> would be helpful.
> Do you mean add single string JDOQL of the examples to the spec or  
> provide them for this email discussion? I agree it would be useful  
> to add them to the spec. If you are just interested for right now:
> - employees who work more than the average of all employees
> SELECT FROM Employee WHERE this.weeklyhours > (SELECT AVG 
> (e.weeklyhours) FROM Employee e)
> - employees who work more than the average of their department  
> employees
> SELECT FROM Employee WHERE this.weeklyhours > (SELECT AVG 
> (e.weeklyhours) FROM this.department.employees e)
> - employees who work more than the average of the employees in  
> their department having the same manager:
> SELECT FROM Employee WHERE this.weeklyhours >
>   (SELECT AVG(e.weeklyhours) FROM Employee e WHERE e.manager ==  
> this.manager)
>
> Christiaan,
> yes, I think the query code you added to your email returns the  
> same result.
>
> Regards Michael
>
>> -matthew
>>
>> On Oct 25, 2007, at 5:07 AM, Christiaan wrote:
>>
>>>
>>> Hi Craig,
>>> the examples are very informative. I must say that I find the  
>>> description
>>> for candidateCollectionExpression
>>> "The candidateCollectionExpression is the expression using tokens  
>>> from
>>> this query that represent the candidates over which the subquery is
>>> evaluated. "
>>> a little bit cryptic (I actually find the paramater name more  
>>> descriptive
>>> than the description). Especially "tokens from this query" (is  
>>> tokens a
>>> common word for this and may be it should be stressed that this  
>>> query is the
>>> outer query?) and "over which the subquery is evaluated", but may  
>>> be this is
>>> needed for the spec.
>>>
>>> Anyway, do I understand it correctly that it is the same as:
>>> ....
>>> sub.setFilter(":departmentEmployees.contains(this)");
>>> Query q = pm.newQuery(Employee.class);
>>> q.setFilter("this.weeklyHours > averageWeeklyhours");
>>> q.addSubquery(sub, "double averageWeeklyhours",  null,
>>> "this.department.employees");
>>>
>>> kind regards,
>>> Christiaan
>>> -- 
>>> View this message in context: http://www.nabble.com/Subquery- 
>>> specification-update-tf4686785.html#a13405438
>>> Sent from the JDO - Development mailing list archive at Nabble.com.
>>>
>
>
> -- 
> Tech@Spree Engineering GmbH  Tel.: +49/(0)30/235 520-33
> Buelowstr. 66                Fax.: +49/(0)30/217 520-12
> 10783 Berlin                 mailto:mbo.tech@spree.de  
> Geschaeftsfuehrung: Anna-Kristin Proefrock
> Sitz Berlin, Amtsgericht Charlottenburg, HRB 564 52
>

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


--Apple-Mail-113-272658962
Content-Transfer-Encoding: base64
Content-Type: application/pkcs7-signature;
	name=smime.p7s
Content-Disposition: attachment;
	filename=smime.p7s
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--Apple-Mail-113-272658962--