Re: Database design

Roy Hann schrieb:
> "Mark Johnson" <102334.12_at_compuserve.com> wrote in message
> news:acrfv1l86m3aqgfc2a3gj1btrbm1ja8r6p_at_4ax.com...

>> "friend.05" <hirenshah.05_at_gmail.com> wrote:
>>
>>> I want to desgin a database for Tag Structure. Database design that can
>>> store heirarchy of tags developed my users.  Present most popular tags.
>> You are asking if a relational database, with its flat
>> tables/relations and link keys can be used to store nested markup -
>> such as XHTML.

There is two separate issues:
- multidimensionality, and
- hierarchy
"Flat" in this context means (as far as I understand) the absence of hierarchy, i.e., all the elements are at the same level. Naturally this has nothing to do with n-dimensionality, i.e., n-dimensional model can well be flat (non-hierarchical) and vice versa a hierarchical model might well be one-dimensional. An example is any relational model which is intrinsically non-hierarchical (that is, flat). Here it is also assumed that the model itself is unaware if there is a hierarchy in the data it models or not because it does not care - it is based on other principles. However, the designer may well use it to model a hierarchical data (as well as many other types of data organization). In this case he/she must be responsible for the hierarchy maintenance (integrity etc.) For example, we might model a tree but the model does not know that it is a tree and hence cannot help us in its use.

-- 
http://conceptoriented.com