NBLUG Library ?

[Eric Eisenhart]

On Thu, Oct 24, 2002 at 03:42:06PM -0700, Ron Wickersham wrote:
> this is not something i understand very well, but the problem shows up in
> the structure and rules for the MARC records, which fit multi-valued
> database model (like pick).
>  
> a search in the koha archives didn't yield the pages i read, but i did
> find this link that sounds similar to the issues raised on the koha list:
> http://sunsite.berkeley.edu/XML4Lib/archive/0112/0010.html

That page talks about the proper relational method for creating
"multi-valued fields" being complicated enough that it's a hassle.

Example:
DB with multi-valued fields where you give up on proper relational stuff:

Foos
----------
id  |int
name|varchar
bar |multi-value [one, two, three]

DB without multi-valued fields, doing single values:

Foos
----------
id  |int
name|varchar
bar |int

Bars
----------
id  |int
name|varchar


DB without multi-valued fields, doing real multi-valued stuff:

Foos
----------
id  |int
name|varchar

Bars
----------
id  |int
name|varchar

FooBar
----------
foo |int
bar |int


In other words, in a database with explicit "multi-valued fields", you have
a single table with one field that's "extra special".  Without explicit
"multi-valued fields" you create one table holding the potential values and
another table holding the link between available values and the record.
-- 
Eric Eisenhart                                  eric-dot-sig at eisenhart.com
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