cayenne-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Robert Zeigler <robert.zeig...@gmail.com>
Subject Re: General queries
Date Wed, 08 Apr 2009 19:50:03 GMT
Well, Cayenne doesn't "force" you to use SQL.
What it /does/ do is to /allow/ you to use SQL.
An app I wrote awhile back had the requirement to generate reports  
from tables with on the order of a million records.
There was no substitute for hand crafted, carefully optimized  
queries.  Cayenne makes it easy to do that, if the need arises, via  
SQLTemplate.
But SQLTemplate offers more than "just" SQL.  You can script it (via  
velocity [http://velocity.apache.org] directives and variables); you  
can write customized queries for different backends (MySQL, HSQL,  
Oracle, etc.) which then "just work" based on which backend you're  
connected to (ie: in your code, you don't have to think about which  
backend you're connected to).

But, if you're interested in sticking to object paths and  
relationships, EJBQLQuery provides a nice alternative.

Robert

On Apr 8, 2009, at 4/82:27 PM , Weddle, Anthony wrote:

> Thanks, Andrus. I'll take a look at EJBQL and may have to revisit
> SQLTemplates. It's not that the latter is scary, just that it  
> appears to
> be native SQL, rather than being able to used property paths and class
> or object entity names. We're using an ORM framework to avoid native  
> SQL
> wherever we can, so wouldn't want to switch to a framework that forced
> us back to more of it.
>
> One of the main problems I'm having is that there is so little
> documentation, books and articles about Cayenne. Is there a fairly
> comprehensive list of publications (not necessarily books) on Cayenne?
>
> Tony
>
> -----Original Message-----
> From: Andrus Adamchik [mailto:andrus@objectstyle.org]
> Sent: Wednesday, 8 April 2009 5:46 p.m.
> To: user@cayenne.apache.org
> Subject: Re: General queries
>
> Cayenne 3.0 includes support for EJBQLQuery which seem like you what
> you need here:
>
>   http://cayenne.apache.org/doc/ejbqlquery.html
>
> We are following the JPA syntax per JSR-220
> (http://jcp.org/aboutJava/communityprocess/final/jsr220/index.html
> ). At does support aggregates, separate columns, subqueries, etc.
> Anything not supported by the EJBQLQuery will indeed require a
> SQLTemplate, which is not as scary as it sounds.
>
> Hope this helps.
>
> Andrus
>
>
>
>
> NOTICE - This message and any attached files may contain information  
> that is confidential, legally privileged or proprietary.  It is  
> intended only for use by the intended recipient. If you are not the  
> intended recipient or the person responsible for delivering the  
> message to the intended recipient, be advised that you have received  
> this message in error. Any dissemination, copying, use or re- 
> transmission of this message or attachment, or the disclosure of any  
> information therein, is strictly forbidden. BlueScope Steel Limited  
> does not represent or guarantee that this message or attachment is  
> free of errors, virus or interference.
>
> If you have received this message in error please notify the sender  
> immediately and delete the message.  Any views expressed in this  
> email are not necessarily the views of BlueScope Steel Limited.


Mime
View raw message