Re: codd's 12 Rules

I wondered if someone might balk about rule # 9.

Rule 9: Logical data independence:
Changes to the logical level (tables, columns, rows, and so on) must not require a change to an application based on the structure. Logical data independence is more difficult to achieve than physical data independence.

I think people could site examples of IBM i following each and every rule. But like any field of interest, you'll find people who interpret rules more narrowly or more broadly than others.




----- Original Message -----
From: Charles Wilt <charles.wilt@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Cc:
Sent: Friday, May 17, 2013 12:43 PM
Subject: Re: codd's 12 Rules

I seem to recall hearing that no current RDBMS meets all of Codd's rules..

http://www.cse.ohio-state.edu/~sgomori/570/coddsrules.html

"Note that based on these rules there is no fully relational database
management system available today. In particular, rules 6, 9, 10, 11 and 12
are difficult to satisfy."

Charles