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)