The relational model, half a good ideaPresentation of the relational modelWe start with all the cards used to exercise an activity. We apply a certain number of rules for simplifying and making the different types of files consistent, described in the Merise method, and we arrive at a canonical representation of the information to be processed, which we will call the relational model. From there, concretely, in the computer system, we no longer store the files, but their representation in the established relational model, that is to say their embedding in the set of tables which constitutes it. The method for building an information system on the basis of the relational model was formalized in the 1970s under the name 'Merise method'. ↣ More details about the Merise method The contribution of the relational model
To exercise its activity, a company needs not only files, but also reports which are the copying and possibly the reconcentration of data extracted from the files, thus providing the relevant additional information for each activity. The great thing about the relational model is that it's easy to add new states to extract new, relevant information from the same set of cards. The limits of the relational modelThey are triple: On the one hand, if we slightly change the cards handled to take into account a change in activity, nothing says that the consequences at the level of the relational model will be slight. Second, as soon as you want to reconcile data from several different organizations, the benefits of the relational model quickly drop. Finally, this model increases incomprehension between users who think of the activity in terms of records, and IT specialists who think of the activity in terms of tables and therefore relational model. Consequences on the mode of organization in the companyLe modèle relationnel consiste à obtenir au terme d'un long travail préparatoire une sorte de représentation parfaite de l'activité qui est au final contre productive puisqu'elle va pousser l'entreprise à voir les évolutions ultérieures comme la perte de la perfection originelle et voir le monde extérieur comme un environnement hostile car non conforme aux règles sous tendant la perfection intérieure. CRM, ERP (ERP) and other organizational software are all based on a relational model that is adapted at the margin at the time of deployment. Not only do they not escape the difficulties inherent in the relational model (difficult evolution and interconnection), but also the real company that equips itself generally turns out to be different from the modeled ideal; it is in fact often forced in the end to adopt the rules established for the virtual company targeted by the software. |