Re: Database Model - Class, objects and interaction

Responding to Jacobs...

This response is directed primarily at the OP. So don't get your hopes up that I will participate in one of you chain-pulling exercises.

You then encapsulate those abstractions as a cohesive subsystem behind
an interface that is tailored to the data needs of your application. If
you capture the invariants of the persistence paradigms properly,

This is misleading. Databases are about much *more* than just
"persistence". Sure, you can use them for only persistence, but that
would be a waste of tools in most cases.

Separation and isolation of concerns is fundamental to managing complexity at any level and in any environment. In a computing environment it is a fundamental mistake to merge problem solving and data storage because they are quite different subject matters with quite different invariants.

That can work for niche processing like CRUD/USER where you live because the form-based presentation paradigms have been deliberately defined to map into RDB structures easily. IOW, the computing can be abstracted into a specific RAD IDE paradigm for the sorts of DB/UI pipeline applications where the major problem being solved is data entry and presentation. That is, the user does the data analysis and reacts to it once it is in a convenient format, not the application.

But for applications that solve complex business problems that involve actually analyzing and processing the data it just leads to unmaintainable applications. In those cases the concerns need to be separated. You can use DBMS-based tools for things like reporting on inventory activity, but if you try use such tools to manage the inventory it would be a maintainability disaster in the long term. Not to mention that the table-level query/join philosophy would be horrendously inefficient for the solution since the same data is likely to be accessed repeatedly during algorithmic processing.



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H. S. Lahman
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