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gadfly RDBMS ???

Dennis Lee Bieber wlfraed at ix.netcom.com
Wed Jul 21 23:27:14 EDT 1999 
On Wed, 21 Jul 1999 17:42:55 +0200, Darko Cvagic
<darko.cvagic at arcus.tel.hr> declaimed the following in comp.lang.python:

> 
> 
> Thanks, I think that I'm exchange terms like RELATION and LINK
> So, Gadfly IS RELATIONAL, but I can't make something like:
> 	CREATE LINK order_customer
> 	FOREIGN KEY order(cno)
> 	REFERENCES customer
> 	ON DELETE RESTRICT
> 
> I can't do it in gadfly, am I wright?  
> What is name for construction like this? 
> I was thought that it is RELATIONAL , I was wrong!

	That sounds like a definition of referential integrity
constraints... I've not looked at gadfly -- perhaps it doesn't actually
maintain such internally, but only via SQL select statements, which
would require one to code the integrity tests themselves...


	It is confusing in a way -- based upon some readings of my old
DB textbooks, "relation" in "relational" doesn't really apply to
linkages between tables. The "relation" is that the key value /in/ the
table uniquely identifies the "related" data values, and that each
"record" (tuple in the texts) of a table is identical in format to every
other in that table.

	Relational algebra and calculus are methods of selecting data
from multiple tables to produce a result -- but again, these do not
enforce referential integrity. In truth, "relational" is a view of the
data, which may be stored in any format -- even in hierarchical or
network format.

	I think I begin to ramble...
 
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