Re: c.d.theory glossary - RELATION

x wrote:

> mAsterdam wrote:

>>x wrote:
[snip]
> If the facts tell nothing about things in the world,
> then a relational database would be worthless (empty) :-)

:-)

>>>If yes, those  _things_  are explicitly or implicitly represented
>>>in relational model ? And by what ? Why not otherwise.
>>
>>Assuming yes about the first question:
>>'represent' would be 'explicit', imho.
>>By what? By the propositions (by means of the predicates).
>>
>>As I said: just thinking out loud.

The proposition "John likes Mary" represents John. Indirectly, but explicitly. Like so:

"John likes Mary" would be in the body of a relation. It's predicate would be (short) "<Person> likes <Person>".

A representation would be:

+----------------------------------------+
|Likes:                                  |
| The person identified by Person1 likes |
| the person identified by Person2       |
+--------------------+-------------------+

+====================+===================+
| John               | Mary              |
+--------------------|-------------------+

While we're at it:
An ER-model would have one box "Person", with a recursive m:n association 'likes/is liked by'.

Are you sure he likes her? Received on Fri Apr 30 2004 - 17:58:12 CEST