RE: Supertypes?
От | Christian Marschalek |
---|---|
Тема | RE: Supertypes? |
Дата | |
Msg-id | 000401c0b6ee$b30e3ba0$0200a8c0@server обсуждение исходный текст |
Ответ на | Supertypes? ("Christian Marschalek" <cm@chello.at>) |
Список | pgsql-general |
Oh yeah we've learned about the normal forms too :) It's all flying back into my mind right now ;o) Thx! > -----Original Message----- > From: Gregory Wood [mailto:gregw@com-stock.com] > Sent: Tuesday, March 27, 2001 5:04 PM > To: Christian Marschalek > Subject: Re: Supertypes? > > > > Well we've learned that when you have lets say five tables > which all > > contain name, adresse, city and so on you also have a form of > > redundancy... Can be wrong, though ;o) > > When dealing with relational databases, that redundancy (or > the process of eliminating it) is called normalization. This > usually involves breaking tables apart into smaller tables. > There are several 'normal forms' which database designers > strive for... each normal form is closer to the 'ideal' > database, although most designers don't bother with much > beyond 3rd normal form. Of course, it can be wise to break > the rules for performance reasons... > > Anyway, I highly recommend reading up on the topic... I > didn't when I first started playing with SQL and look back on > those days as my little database 'Dark Ages'. > > Greg > >
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