On 23/12/10 22:03, [email protected] wrote: > In a message dated 12/23/2010 11:14:45 AM Pacific Standard Time, > [email protected] writes: > > >> Actually, I'd disagree with you. Applications are all about the >> METAdata, which a relational database throws away. ALL relational APPS >> contain an awful lot of logic to manage stuff that SHOULD be managed in >> the database - except an RDBMS has no way of managing that information >> so it can't be managed in an RDBMS. >> >> I talked about adjectives out there in the real world. Adjectives >> describe nouns. What's the database equivalent of a noun? That's right, >> in an RDBMS there is NO SUCH EQUIVALENT. > > Can you give those of use who are more dense, a concrete, specific example > of what you're talking about? > I've seen several messages like this, and still don't comprehend it. > > Do not first-normal form databases have column headings? Aren't those > headings the names of the attributes (nouns if you will)? Or the table names > the names of the nouns.
First Normal Form databases are two-dimensional. Table and column names are irrelevant here, the question is how do you *store* a "noun-thingy" IN the database, not how you define the database. Let's take a car ... Let's define a relational table called CAR. Let's key it off the VIN, which should be a unique id. Add a column called REG ... oops - cars can have multiple registrations over the years, so we can't put the registration in the CAR table. Now let's create a column called COLOUR ... oops, a car can be multi-coloured, so we can't put the colour in the CAR table. etc etc etc. The point is, a well designed MV database has ONE file that contains ALL the attributes for any given entity - each "row" contains a *complete* instance of a "noun", each column contains *all* the values of the "adjective" that describes that "noun". In an MV-dbms, ALL the data about any one car is stored in one record in one file. In an RDBMS, ALL the data about any one car is plastered across many rows in many tables. > I'm still not seeing why you can't simply create an MV file for each Table, > a record for each row, and an attibute for each column. > Where's the problem? Because if you do this you do not have a Multi-Valued database. You have a relational database in a multi-value engine. In other words, the *worst* of both worlds. There's nothing stopping you doing it. You just don't end up with a Multi-Valued database at the end of it! I recognise your addy. Surely you know all this? It's all pretty basic MultiValue! Cheers, Wol _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users
