Documentary approach - Databases: design

Documentary approach

The study of the documentary composition of the subject area has always been and remains one of the most important stages in the design of databases.

It is the document that gives the maximum amount of information about those components (attributes, links, structures) that should be reflected in the database model. Many information systems are focused on working with documents, without allocating other information structures and thereby severely limiting the processing of information. However, this approach to building an information system is also justified, when the goal is to organize the work of an employee, division, organization on the basis of workflow and work with documents.

This work with data has long been virtually the only option for considering data structures, especially in the absence of specialized approaches and tools for modeling the organization's biases, as well as reviewing the activities of the organization, division, employee as a source and consumer of information presented in form of documents. The main paradigm in organizing the organization's activities has always been the work with documents. And this is absolutely correct, since only the document can contain all the necessary information for the work. The documentary approach is usually applied when it is necessary to make any decisions.

The process of using the documentary approach in database design is represented in the following sequential steps.

1. Allocating the composition of documents used in the domain.

2. Allocate the composition of users of documents, dividing them into consumers, compilers and fillers, as well as internal, external and system.

3. Forming the scheme of document circulation between users of documents, illustrating not only the communication of users through documents, but also the direction of document movement, taking into account external users.

4. Selection of attributes from documents, specifying them with data types, usability, variability, semantic loading, etc.

5. Creation based on attributive entity attributes.

6. Establishing direct and indirect links between attributive

entities.

7. Normalization of the obtained database model according to the rules of technical and logical normalization, taking into account the rules of transition between normal forms.

8. Construction of the final (publication for various categories of participants in the development process) database model.

As it is obvious from the composition of the stages of building a database model using the documentary approach, the developers do not take into account the functional content of the work with documents, which guides the database model to solve the problems of information content and the formation of initial document structures, not taking into account the intermediate tasks, the necessary data structures ensuring high-quality storage and processing.

Of course, you can consider the subject area, taking into account the division into functions and tasks, this approach can lead to the emergence of identical entities with different attributive composition, which will require several more iterations to normalize the database model.

The first stages of considering the subject area in the information plan are the identification of documents, their structures and traffic between users, which for convenience of further consideration and use in the development process of the database is presented in the form of specification tables and corresponding diagrams, some of which were considered earlier . As a result of this examination, within the used example of the electronic store, the developer has selected a certain set of documents (Table 4.1).

Table 4.1

Example of selected domain documents

No. п/п

Document

Description/Description

1

D1

Document Order

The composition of the document is represented by an indication of the client (organization or individual), the date of compilation, the list of goods that the client ordered, indicating the price, quantity and value for each item and the total value of the order in numerical and symbolic terms. The document is generated by the client in the filling process of the "shopping cart" goods and will be transferred to the operator and the sales manager

2

D2

Document Demand-waybill

The composition of the document determines t