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Re: [agileDatabases] Re: Test Driven Database Design

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  • Malte Finsterwalder
    ... Actually TopLink does support this feature. You can write a SQL select and TopLink creates your object from the result set. But it s not the standard
    Message 1 of 20 , Feb 25, 2003
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      Bryan Hughes wrote:
      > From my experience, I have found
      > that agile system needs to be coupled with the SQL, not the tables and columns.
      > Unfortunately, all of the ORTools we evaluated did not allow a means to describe
      > the query directly.

      Actually TopLink does support this feature. You can write a SQL select
      and TopLink creates your object from the result set. But it's not the
      standard procedure and as such it's not very well supported.

      Greetings,
      Malte
    • Pramod
      have you seen Jaxor.. http://jaxor.sourceforge.net/ Pramod ... ===== __________________________________________________ Do you Yahoo!? Yahoo! Tax Center -
      Message 2 of 20 , Feb 25, 2003
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        have you seen Jaxor..

        http://jaxor.sourceforge.net/

        Pramod
        --- "Malte Finsterwalder <finsterwalder@...>"
        <finsterwalder@...> wrote:
        > Hello Bryan,
        >
        > first of all, thank you for your interesting post.
        > I was having similar ideas to what you said, but
        > didn't get to try
        > anything yet.
        >
        > Bryan wrote:
        > > Because of these circumstances, I developed a
        > system to do in-place data
        > > migrations on a production database without having
        > to take it down. I
        > > have also developed an ORFactory which
        > manufactures Java Classes based
        > > on a resultset. This is another area that I feel
        > is a mistake for
        > > Object Relational Tools. They always try to map
        > to table/column and
        > > figure out relations and table order, when they
        > should be mapping to the
        > > resultset of a query. It is the results of the
        > query that any database
        > > server return - not tables and columns. By using
        > queries to return
        > > resultsets which then are used to either write
        > Classes or Reflected
        > > into, you decouple your application from the
        > database. The data access
        > > classes contain no logic, just the CRUD (Create,
        > Read, Update and
        > > Delete) and getter and setter methods, as well as
        > some collection
        > > handling.
        >
        > Do I understand correctly, that you construct simple
        > Data-Holding
        > classes in your ORFactory that contain the data from
        > the resultset? So
        > those objects probably only have getters and
        > setters?
        >
        > How do you use those objects? Do you use them to
        > initialize business
        > objects from them? How do you feed changes in you
        > business-objects
        > back into the data-objects? Or do you construct new
        > data-objects? Do
        > the business-objects do that themselves, or do you
        > have another class
        > that does the creation of data-objects from your
        > business objects?
        >
        > And what is the relation to your business-objects?
        > One-on-one? Why
        > didn't you build business-objects themselves from
        > the resultsets? (I
        > know this might result in inflexible couplings, but
        > which coplings in
        > particular?)
        >
        > > Sorry for the loooong email, but I have been
        > meaning to contribute and
        > > am planning to post an essay describing exactly
        > how to build the system
        > > I have described.
        >
        > I would be very much interested in that essay!
        >
        > Greetings,
        > Malte
        >
        >
        >


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      • Malte Finsterwalder
        ... I just browsed over it. But I m not concerned about HOW to map objects to tables. I m interested in WHICH objects are mapped to tables. And since the
        Message 3 of 20 , Feb 25, 2003
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          Pramod wrote:
          > have you seen Jaxor..
          >
          > http://jaxor.sourceforge.net/

          I just browsed over it.

          But I'm not concerned about HOW to map objects to tables.

          I'm interested in WHICH objects are mapped to tables.
          And since the objects that are mapped to tables are simple data-objects,
          HOW are they used? Which other objects access them? How are they updated
          and such.

          Greetings,
          Malte
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