Hi Fedor,
I like the API (or rather the usage) part of nqm.
I have bit of a concern with the implementation though. We develop mostly
on Interbase, but mostly we deploy on MySQL or Oracle. The biggest problem
I have with current Criteria objects when you do something like:
WHERE a > x AND a < x
where x is a Date. Databases require that you give them dates in formats
that they prescribe. I fixed it in the Criteria/Criterion objects by making
use of a PreparedStatement. This moves the responsibility to the JDBC
driver.
I'd like to see something similar in nqm. This can possibly be done by
adding parameters to the SQLCode interface. Something like this:
public StringStackBuffer toSQL(DB db, List params);
What do you think?
We can develop nqm in parallel with Criteria. All the needs to be done is
to add the extra methods to the Torque generation classes. A simple #if can
determine whether to create the Criteria methods or the nqm methods.
Just my 2c for a name (I don't really care, but you asked for it) Advanced
QUery MOdel = aqumo.
~ Leon
----- Original Message -----
From: "Fedor Karpelevitch" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, May 09, 2001 10:02 AM
Subject: [PROPOSAL] New Query Model
> Hi!
>
> here is the deal:
>
> Latest activity around Criteria inspired me to try to reimplement the
whole
> idea. I drafted some code which i will check in shortly into
> proposals/fedor/nqm (the code is not going to compile, it's just draft)
>
> The basic idea is to refactor & rename everything to make it more OO,
solve
> problems Criteria has hard time with, make code duplication virtual zero
and
> make it flexible enough to be able to adopt future needs.
>
> here is how it breaks down:
>
> the select criteria or conditions are all represented by Condition
interface
> (it is similar to current Criterion)
>
> the class hierarchy of Conditions looks like this:
>
> Condition
> |
> |----> Comaprison ----> Equal, NotEqual, More, Less etc...
> |
> |-----> ComplexCondition ----> And, Or
>
> (Yes, I know "ComplexCondition" sounds very medical, go ahead and suggest
a
> better name)
>
> so when you need to get SQL like this:
>
> WHERE A.B=3 AND A.C>5
>
> you'd create the Condition like this:
>
> new And().add(new Equal("A.B", 3)).add(new More("A.C", 5);
>
> if you need smth more complex (pain with Criteria):
>
> WHERE (A.B = 5 and A.C=7) or (A.B=7 and A.C = 15)
>
> is done like this:
>
> new Or()
> .add(new And()
> .add(new Equal("A.B", 5))
> .add(new Equal("A.C", 7)))
> .add(new And()
> .add(new Equal("A.B", 7))
> .add(new Equal("A.C", 15)));
>
>
> uff... hope you won't have to do that, but at least it does not require
any
> nasty hacks and does not take a lot of extra code....
>
> now, that's just WHERE clause, but for a sql query we need a little more
like
> select columns, orderby's etc... For that there is Query object which if
> functionally is Criteria less Conditions.
>
> The inheritance here looks like this:
>
> Statement
> |
> |-----> Query
> |
> |-----> Update
> |
> |-----> Delete
>
> Statement provides common stuff like WHERE and FROM clause.
> Query also has methods like addSelectColumn, addOrderByColumn etc...
>
> So I am asking for comments/ideas/money ... sorry, no money.
> And I propose this as a replacement to current Criteria and related
classes.
> Appropriate methods should be added to Peers & OM which would take
Condition
> or Query instead of Criteria. At the point when it's fully functional &
> stable Criteria & corresponding Peer methods would be deprecated and at
some
> point removed.
>
> Also couple of smaller points: I think those new classes should go into
their
> own package at least to make it clear where the new stuff is and where is
the
> old one. What do you, guys, think? Also any ideas for the name of the
package
> - the best I could come up with is "nqm", which I do not like...
>
> Fedor.
>
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