La logique informatique
(selon les travaux de J.D WARNIER)
L.C.S organizing data in a computer system
Study of the Primary Logical Files of a logical database.
What is a F.L.P (Primary Logical File ) ?
A primary logical file is a file containing articles or records (according to the vocabulary that computer scientists use) in the same format.
The same format ? But that's what it means "the same format"?
Here is the mathematical rule that answers this question:
When the fields of two records match in a bijection, these records are said to have the same format.
If we want to understand the phenomenon, it is necessary to see that the recordings of a file are the images that one wishes on the objects of the same nature that includes this file, that each record is the image of an object, and a field of a record, is a part of that image of the object.
Thanks to this mathematical rule, we obtain the assurance that all images of objects of the same file are strictly identical.
We will now give an example of subdivision of a database in order to discover our FLP's, this is only a simplistic example certainly, but it has the advantage to help you see how (after study of the exchanges maintained by the Third Parties With the company) one discovers the FLP's of a base.
Let us suppose for our example that we wanted to subdivide the base for external customers of a main activity for a company ' X ' specialized in heating products, the products sold are different in nature because of the fuel used (wood, fuel, etc.). .)
The proposed subdivision is as follows :
You will notice that the subset of the data relating to the exchanges has been subdivided according to the usual stages of an exchange :
Order, delivery, invoice and payment.
Another remark is that, it is preferable to make a complete study of the FLP's of the studied base, at least, the complete study of the flows of production or of the financial flows, and let us not forget to define each FLP "by understanding", because in Little time we'll put stuff in !