Re: The original version

> It is bad design when one just puts numbers into a database and uses
> these numbers as identifiers or as “surrogate keys”. This technique is
> especially bad for databases that maintain history, because the
> following two cases are possible:
> 1. one identifier can identify two distinct entities;
> 2. two distinct identifiers can identify one entity;

Example: Let E1 and E2 be two entities of the same type. Suppose they change the value of their properties. It is quite clear that this can happen at the same time and that E1 and E2 can have all of the exact same attributes. That which is very bad for Anchor Modeling here is that the identities of these two entities are different, even though these two entities are exactly the same in the database, and in the real world.

In this example, a variety of combinations and variations can occur, especially since the authors of Anchor Modeling allow the deletion of erroneous data.

Vladimir Odrljin Received on Tue Jan 11 2011 - 00:53:25 CET