Informal Survey #1 -- joins on foreign keys
From: Rob <rmpsfdbs_at_gmail.com>
Date: Sat, 1 Oct 2011 10:09:37 -0700 (PDT)
Message-ID: <469d9627-f72a-4720-a5ea-ec1171291e0e_at_k10g2000vbn.googlegroups.com>
First, let me qualify my interests. I am primarily interesested in the mechanics of
relational database management, not the semantics. I am interested in the evaluation
of sql queries without regard to their meaning.
Date: Sat, 1 Oct 2011 10:09:37 -0700 (PDT)
Message-ID: <469d9627-f72a-4720-a5ea-ec1171291e0e_at_k10g2000vbn.googlegroups.com>
First, let me qualify my interests. I am primarily interesested in the mechanics of
relational database management, not the semantics. I am interested in the evaluation
of sql queries without regard to their meaning.
- without racking your brain or searching the archives of your previous work, does your gut feeling tell you have ever authored or seen an sql query in which two relations were joined on a foreign key in each?
- using your knowledge and understanding of (any) relational algebra, is a join between two relations on a foreign key in each ever meaningful? (Keep in mind the definition of the domain of a foreign key.)
- in the semantic realm you use to "think about" relational databases (i.e., E-R, facts, etc.), does a join between two relations on a foreign key in each make sense?
I request that you spend at least 10 minutes thinking about this
before you flame
me.
Rob Received on Sat Oct 01 2011 - 19:09:37 CEST