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Fundamentals

Relational Models and OO

Object-oriented theory and relational algebra

Original: Zhang3, 2011-04-19

1. Relational algebra is a subset of first-order logic and what it represented is, the logical relationship between things.

2. E-R model has deviated from the real  intention of  relational logic. The ‘E’ should not be an entity but just a name. Relational modeling should not by the E-R way.

3. Some of well design patterns be destroyed by OO analysis. Most people lay the blame on that the idea of database is not advanced than the idea of OO. However, in fact, the relational algebra is much profound than the OO theory (if even say that OO having some theory).

4. Some models will be simple in relational database, which are complex on OO thinking, and will be simpler if the relational database providers a Turing-complete language instead of the SQL way.

5. ORM is a serious mistake, which forced modeling a real world relationship by OO, and then mapping it onto a relational database, that is, to build a bridge incompatible to both, between two originally compatible worlds. Nothing is more absurd than this.

Original URL: http://www.douban.com/note/146255104/

(Translated by TY)

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About TY

interested in models & modeling, software, information systems, applications & engineering for enterprises

Discussion

2 thoughts on “Relational Models and OO

  1. “4. Some models will be simple in relational database, which are complex on OO thinking, and will be simpler if the relational database providers a Turing-complete language instead of the SQL way.”

    Are you really sure you want to handle such a language? SQL is mainly based on FO (1st Order Logic) and is extended punctually – by counting capabilities etc.

    Alternatively one could extend it to a SO (2nd Order Logic) based language – i.e. queries containing relations of relations. Thus the price for this increase of expressiveness, would be a language that is much more complicated – not only to read/ write, but also to implement for DBMS.

    This is the classic language design trade-off.

    Have fun
    |=

    Posted by modelpractice | June 7, 2011, 18:30
    • Mainly, I agree your comment, I think, an idealized ‘SQL’ may be has more stringent relational algebra, and supporting or expanding mechanism to that from first order logic to more advanced logic.

      (The author, Zhang3, developing a new language/IDE based on prolog… I might not very understanding his idea.)

      Posted by TY | June 7, 2011, 19:27

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