Re: Creating table as datatype

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От Joris Dobbelsteen
Тема Re: Creating table as datatype
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Msg-id E4953B65D9E5054AA6C227B410C56AA9C357@exchange1.joris2k.local
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Ответ на Creating table as datatype  (rasoolbv <rasoolbv@yahoo.com.sg>)
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>-----Original Message-----
>From: pgadmin-support-owner@postgresql.org
>[mailto:pgadmin-support-owner@postgresql.org] On Behalf Of rasoolbv
>Sent: Thursday, 14 February 2008 6:42
>To: pgadmin-support@postgresql.org
>Subject: [pgadmin-support] Creating table as datatype
>
>
>Hi, I am new to this ordb, postgresql and pgadmin. I am using
>this for a project that involves lots of object aggregation
>and inheritance.

Look for documents about the Relation model and normalization.
For example: <http://en.wikipedia.org/wiki/Database_normalization>
Others might have very good links, search the archives and the archives
of the postgresql-general mailing list.

Inheritance is a quite hard subject in the relational model and opinions
on whether and how to use here may vary quite a lot. Personally I think
it can give quite a few problems and you should use it very sparingly.
Use other means to archieve the same result.

>Currently I am able to create a column as of datatype. That
>is, for a staff I can have a multivalued column of datatype
>internalAddress. I want to create a table of a datatype. That
>is for instance, a table of datatype staff and this is later
>to be part of a company. I don't seem to find this option
>available. Hope to get some help in this.

Your paradigms are closely related to Object-Oriented programming. The
relational model is slightly different.
You need to see your database types more as tables or relations (note:
table and relation have the same meaning, the naming might be confusing,
but it has it roots in mathematics (logic and set theory) and the other
more in computer science).

- Joris



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