RE: relational database

Rob,

Yes I do believe that data is relational. Just because you've stored two different relational tuples on the same physical file doesn't mean it's not relational. It's got a key which I can use to retrieve a detail record directly by order number/line number. With the alternative CODASYL hierarchal or network database I'd have to follow a pointer chain route through the header to get to the detail. CODASYL databases have external definitions too so external definitions do not define a relational database.

Paul Morgan

Principal Programmer Analyst
IT Supply Chain/Replenishment


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Tuesday, February 08, 2011 11:12 AM
To: Midrange Systems Technical Discussion
Subject: RE: relational database

I really do not think that the S/36, S/34 and their predecessors qualify
as relational database machines simply because they supported a chain by a
key instead of just RRN in RPG.

Do you really think the data below is relational?
A0000100012345Bubba 1313 Mockingbird Lane New York NY12345
A00001001XYZ123Steel Coil ...

Hey, I can chain to the first key by order number 00001 and line number
000 (indicates header record). And I can chain to the second by order
number 00001 and line number 001 (>0 indicates a detail line). Who needs
externally defined files? Apparently that's not even required to be
considered a relational system. Just an ability to chain by a key instead
of a RRN.

Rob Berendt