Re: Database design

mAsterdam <mAsterdam_at_vrijdag.org> wrote:

>> A relation is NOT a table
>> An attribute is NOT a column
>> A row is simply NOT a tuple, to the latter of course, I'd agree.

>Not to the first two?

Only because:

>> A relation is a set, which need not be written as a table, to be sure.
>> But in a world of constraints, situation and conditions - in a world a
>> databases and a ng devoted to an aspect of same - I also agree it
>> would be reasonable to speak of relations as tables, attributes as
>> columns, and rows as not . . . entities.

>>>Yet, neither tables nor relations map to entity types.

>> The single row is then called - what?

>In the context of tables, just that: a row.
>In the context of relations: a tuple.

But, okay

>>>One relation may have attributese from several entitiy types,

>> Then an entity type is seen as some unique attribute domain?

>No. Why?

And because a single table may have columns, each of which have different - types? What your definition of - entity? and "entity type"?

>>>and one entity may have data spread across several relations

>> Then an entity type is not some unique attribute domain?

>Indeed not. Why should it?

It appears definitional. Received on Tue Feb 21 2006 - 18:04:20 CST