What is the difference between....
From: Jenski <jenski182_at_aol.com>
Date: 29 Nov 2005 14:01:16 -0800
Message-ID: <1133301676.024496.49780_at_g47g2000cwa.googlegroups.com>
Just wondered, what is the difference between a cardinality ratio constraint and a structural constraint?
Date: 29 Nov 2005 14:01:16 -0800
Message-ID: <1133301676.024496.49780_at_g47g2000cwa.googlegroups.com>
Just wondered, what is the difference between a cardinality ratio constraint and a structural constraint?
Is, a cardinality ratio like 1-to-many, 1 to 1 etc..
and
Structural constraint has (min, max) values? (for each relation?)
e.g. Cardinality Ratio:
Each car must have one registered owner, but an owner can have sevaral
cars
Owner-------<owns>--------------Car
1 M
e.g. Structural Constraint:
Each employee must work in 1 department, but a department can only have
4 employees
Employee -----------<must work>-------------Department
(1,1) (1,4)
PS: Apologies, Google wont let me use tabs.... Received on Tue Nov 29 2005 - 23:01:16 CET