Re: Multiple specification of constraints

ben brugman wrote:

> Constraints should be centralised.

This is to general. I look at it this way: There are more sets of constraints, each with a different purpose. The contraints at the database serve to protect the integrity of the managed set of data. The constraints at the user-interface on the other hand serve to assist the user in providing the data he needs to provide in order to achieve his goal.

So here we have two sets of constraints. Let's call them 'D' and 'U'. You can look at a set of constraints as defining all possible combinations of a set of data, i.e. as a type.

Is U defining a subset of D? A superset? The intersection of the sets defined is the relevant set for the feared constraint-redundancy.

Now when there are lots of data and - relatively - just a few constraints ("Large databanks"), I won't worry about that redundancy. Bank ID's provide a good example for this.

Just my 2 Eurocents. Received on Sat Feb 28 2004 - 09:01:51 CET