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What is the difference between....

From: Jenski <jenski182_at_aol.com>
Date: 29 Nov 2005 14:01:16 -0800
Message-ID: <1133301676.024496.49780@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 - 16:01:16 CST

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