The 3-tier architecture with SQL at the database tier permits (in theory) the ability to swap vendors of the DBMS. The cost is one of performance unless stored procedures are used ... which then end up tying you to the DBMS vendor. ANSI M provides a way out of that problem since the business logic (usually the middle tier) can be combined with the database and the combination can be ported from one vendor's implementation to another with the exact same code and not have to change any "stored procedures" as they are part of the ANSI M code. (Though vendors can certainly have a significant impact on performance).
Greg wrote: I find it useful to think in terms of data types. I believe that what you are saying here is that it is important to abstract away from the primitives used to implement other types. Just as pointers are the basic primitive used in a language like Pascal to implement abstract data types, tuples and relations are the basic primitives used in the relational world to model other structures. I believe it is unnecessarily narrow (and in fact, a caricature of the relational model) to think of the table as the basic *abstraction* of this model. That would be like saying pointers and subfiles are the basic abstractions with which one works in Fileman. That's just not true. They are *primitives* used to model abstractions that can be quite complex. Think about this way: Bricks and mortar may be used to construct buildings (well, maybe not out here in earthquaqke country), but when an architect looks at a building, (s)he does not see (just) brick and mortar. There is much more that can be said about buildings than simply that they are built out of certain fundamental components. > [...] === Gregory Woodhouse ------------------------------------------------------- SF.Net email is sponsored by: Tame your development challenges with Apache's Geronimo App Server. Download it for free - -and be entered to win a 42" plasma tv or your very own Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php _______________________________________________ Hardhats-members mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/hardhats-members
