Re: database design for nesting items

From: Yaron Lapidot <ylapidot_at_netvision.net.il>
Date: Tue, 1 Jun 2004 20:36:18 +0200
Message-ID: <c9ievu$8o1$1_at_news2.netvision.net.il>

if i understand correct u ment to create a table for each attribute ? i 'm not understand .
your suggestion is to use only one table to hold all of the data ( instances) ?
now i want to know which data type i shuld use ? varchar (100) ? i use a forrest design and split my meta tables into 3 parts

1) MetaDocs(MetaDocID,MetaDocName,MetaDocParentID)
2)DocsData(DocDataID,DocParentID)
3) MetaAttributes(MetaAttId,AttName,MetaDocID)

my intension is to create a store procedure ,that create Dynamic Tables by the meta tables
is it so bad ?
any suggestion for another design will be wellcome a lot of thank's for the help
have a good day
Yaron Lapidot

"Brian Inglis" <Brian.Inglis_at_SystematicSw.Invalid> wrote in message news:qaanb05h26ihqaueke0aiahba510cj3tse_at_4ax.com...
> On Sun, 30 May 2004 21:22:46 +0200 in comp.databases.theory, "Yaron
> Lapidot" <ylapidot_at_netvision.net.il> wrote:
>
> >Hello all
> >i've to design a database that hold infomation about documents
> >each document could be a stand alone or a parent of other document/s
> >each document have his own attributes and a uniqe key.
> >
> >my problem is how to hold the attributes of the data.
> >because documents will be create dynamicly i can define a table whice
will
> >hold the attributes data and be
> >varchar data type that can hold all kind of data(a lot of casting work)
> >or define a table for each data type i use ?
>
> If you want to be easily able to query combinations of different
> attributes and retrieve all related documents, put all the document
> attributes into a single table and make each document attribute a row
> in the attribute table: document, attribute name, attribute value.
> If you split the attributes across different tables, you will have to
> write code to generate queries across tables and use different
> combinations of tables for querying about different attributes of a
> single document; perhaps requiring a table relating document
> attributes to table names, never a sign of a good database design.
> If you push the document attribute information into data in a row, you
> can easily write queries relating to any combinations of attributes.
>
> >eventualy i design a tree of documents 'that each doc can hold his own
> >attributes .
>
> Trees are best represented as binary relations in tables holding:
> parent document, child document.
>
> --
> Thanks. Take care, Brian Inglis Calgary, Alberta, Canada
>
> Brian.Inglis_at_CSi.com (Brian dot Inglis at SystematicSw dot ab dot ca)
> fake address use address above to reply
Received on Tue Jun 01 2004 - 20:36:18 CEST