RE: relational database

["Morgan, Paul" <Paul.Morgan@xxxxxxxxxxx>]

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