How can I do this?
Aaron Mulder wrote:
> I think a better solution would be for you to just write some of
> the finders yourself. You can do that, even with CMP beans, and it will
> be *way* faster than waiting for complex features to be added to the core
> server.
>
> Aaron
> On Thu, 26 Oct 2000, Marco wrote:
> > I'm involved in a project using Windows 2K, JBoss and a Database. I'm in
trouble because few stuffs don't work like I want.
> > I need a free Database that offers concurrent access and nested queries.
I built my multi-tier application using InstantDb since my need of a
concurrent access was born later.
> > But InstantDb was too slow and I wanted to change. I used Hypersonic SQL
and mySql but both of them don't allow nested queries. This is a trouble for
me 'cause in JBoss I can't use COUNT, MAX, MIN seen that I can write only
where clause and order by section in queries.
> > In order to fix this trouble I changed my queries using structures like
the following: instead of
> > -- SELECT MAX(fieldname) FROM tablename -- that can not be set in finder
methods,
> > I used
> > -- SELECT fieldname FROM tablename WHERE fieldname = (SELECT
MAX(fieldname) FROM tablename) --
> > that can be!
> > But when I changed database, using Hypersonic and mySql, I discovered I
can use that kind of queries with new databases.
> > So I have two different solution:
> > 1) Ask you to extend tags in finder methods in jaws files in order to
support use of MAX, MIN, COUNT, DISTINCT, etc. In this way JBoss shoul offer
a way to build the first section of sql statements too!
> > I think it should not be an impossible stuff! In this way I could came
back to use first statement I wrote with every database I want! Let me know
if you agree with me when I say it should be a good improvement. Lat me also
know if you need an hand in doing this!
> > 2) Change Database
> > I tried to do this but I had this troubles with:
> > JDataStore: there's no mapping in defaultjaws.xml;
> > Oracle: it's free for developer but hard to install and configure! And I
don't have all of this time!
> > DB2: I think its too hudge!!
> > PostgreSQL: Does a version for Windows exist?
> > And I don't know anything about their performances. Of course I want to
improve my application performances!!! What do you reccommend to me? What
database do you think I should use? What about other databases you offer
type-mapping for in defaultjaws?
> >
> > Let me know if you have any idea that could be interesting for me.
> > Thank a lot,
> >
> > Eng. Marco Pappalardo
> > Ergotech System Inc.
> >
> >
>
>
>
>
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