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 the list of goods that must be issued from the warehouse to be sent to the client, indicating the amount. Formed by the sales manager and transferred to the warehouse

3

dz

Document Sales Check

Composition of the document: indication of the client; list of ordered goods. indication of their quantity, price and value; the total cost of the order in numerical and symbolic terms; date and time of formation; the person in charge; Signs of confirmation (signature) from the responsible person and the client. The document is formed by the accountant and is transferred from the sales manager to the client

4

D4

Document Account

The contents of the document contain information about the client organization, ordered goods, indicating the quantity, price and value, the total cost of the order in numerical and symbolic terms, the manager and the accountant of the seller, the date of issue, the payment term. The document is formed by the accountant and transferred to the client organization

5

D5

Document Invoice

The

The

No. п/п

Document

Description/Description

6

dB

Document Sales invoice & lt; ... & gt;

7

D7

Document Cash receipt & lt; ... & gt;

The

The document descriptions presented in the table determine the main attributive composition of documents, which is supplemented by document forms, from which you can get a complete list of attributes. Also in the description indicate the source and the consumer of the document, presenting information about the document's movement, which allows not only to build a workflow scheme, but also to identify the composition of users of documents. Some documents are used outside the information system, which requires separating the composition of users into internal and external users.

Internal users are the generators of the documents used for the implementation of the organization processes, and presented the staff of the organization. External users are those who belong to the National Assembly of the organization, but form the background information for internal users or receive the resulting documents from the organization. Thus, in the subject area, the following categories of users can be distinguished (Table 4.2).

Table 4.2

Example of the user population

No.

Inside the 11th field

External User

1

2

1

Operator

Customer (individual)

2

Sales Manager

Customer (Organization)

3

Storekeeper

4

Accountant

5

Executive

The

The

For convenience in further use of pointers to relevant users, not to specify the full names, each user is assigned a certain code, which is formed from the table of users by the row and column codes, where the user is specified. For example, for the user Storekeeper & quot ;, located in the line with the code 3 and the 1 column will specify the code & lt; 3.1 & gt; for the user Client (Organization) - & lt; 2.2 & gt ;. Framing the code in angle brackets is due to the fact that it will uniquely identify this code in any description, without confusing it with other codes or description symbols.

As a result of this description, you can form a description of user interaction with documents (Table 4.3), determining the need

The

the formation of certain information needs of users, distributing the access rights to the document.

Table 43

An Example of Distributing Permissions to Documents

No.

Document

User

Access right

1

D1

& lt; 1.2 & gt ;, & lt; 2.2 & gt;

WITH AND WATCH

2

& lt; 1.1 & gt ;, & lt; 2.1 & gt;

AND Ч П

3

D2

& lt; 2.1 & gt;

SIUCHP

4

& lt; 3.1 & gt;

AND Ч П

5

& lt; 4.1 & gt;

Ч П

6

dz

& lt; 2.1 & gt;

Ч П

7

& lt; 1.2 & gt;

h

8

& lt; 4.1 & gt;

WITH AND PART

9

& lt; 5.1 & gt;

and h

10

D4

& lt; 2.2 & gt;

h

11

& lt; 4.1 & gt;

SIUCHP

12

& lt; 5.1 & gt;

ich

13

& lt; 2.1 & gt ;, & lt; 2.2 & gt;

h

14

D5

& lt; 4.1 & gt;

SIUCHP

15

& lt; 2.2 & gt;

Ч

16

& lt; 5.1 & gt;

ich

...

...

...

...

The following notation is used to describe the access character:

• C (creation) - an operation that assumes that the relevant user is the source of the document, forming all of its master data, including the document's death, the date of its creation, and many others, and also fills in some necessary information that is part of its competence;

• And (change) - an operation that determines the possibility of making changes to the document, including the establishment of certain characteristics, the correction of previously made and the addition of new information in accordance with the structure of the document;

• Y (delete) - the right to destroy the document if this document is not yet fixed as a data source or transferred to a subsequent authority for use;

• Ч (reading) - the right to display the document on the screen for the purpose of reading all or part of the data written in it;

• P (print) - the right to publish a document through a printing device, transfer via communication channels or using magnetic media as a separate file.

Of course, this description does not give full information about the rights of access to the document, since there are requirements for accessing users to individual attributes or specific data. For example, sales managers can be divided by product types and then each of them can have the right to modify only the information on the goods belonging to the corresponding type, but to read information about all the goods in the document. These features of access rights are defined when describing individual attributes, preparing information for later use when implementing a physical database (Figure 4.1).

Fig. 4.1. Example of a workflow schema

In this document flow diagram, the names of each user are used for the convenience of reading the diagram for the convenience of reading the diagram, but in complex systems, the workflow diagrams can be quite complex and the use of full names will only hinder the reading of the chart, therefore, it is usually recommended to use code marks users.

Further work on preparing information for modeling a database with a documentary approach requires the description of the attributes of each document (Table 4.4). Since at this stage it is not yet clear how the attributes will be related to each other and how they will be combined, in this description all attributes of each document with their characteristics are presented, based on a logical analysis of the document and the subject area, taking into account the features of the representation of each value of the described attribute. These descriptions will allow the developer in the subsequent modeling to correctly apply the normalization rules and build an effective database.

Table 4.4

Attribute Description by Document

No.

п/п

Document

No.

п/п

Attribute

Type

Data

Description

1

D1

1

Order number

С-Ч

Order number of the order, formed when it is compiled,

11 rCTTs are INCLUDED WITH AND N1 WAVE-HIS CAMERA designation in the format CC-XYY. where the first two characters indicate the type of customer (individual, organization), and the last three characters indicate the ordinal numeric order number

2

Order date

D

The date the order was generated and sent to the store operator for processing

3

Customer

C

Surname, name, patronymic of the natural person or the name of the organization making the order

4

Product Number

Ч

The order number of the goods in the ordered goods table

5

Product

C

The names of the ordered items

6

Number

Item

h

The quantity of goods for each item that the customer ordered

7

Product Price

h

Monetary expression of the cost of a unit of goods with two signs after the decimal point

8

Cost

Item

h

Monetary value of the indicated quantity of ordered goods with indication of two signs after the decimal point. It is calculated the variable of the price of the commodity and its quantity that has been changed

9

Cost

Order

h

The monetary expression of the value of all ordered goods with the indication of two signs after the decimal point. It is calculated by summing the values ​​of the value of the goods but all orders are ordered! I th goods

10

Character

Cost

Order

with

The monetary value of the order value, represented by a symbolic entry

...

...

...

...

...

...

The

The

Similarly, the weight documents of the domain are described. When using database modeling tools, each attribute of a document can be represented by an appropriate entity with a single attribute of an identical name and for which the desired description is generated. The view of this table can be implemented as a report of the resulting database model. However, the use of the tool at this stage is problematic because of the too large number of attributes that will be generated.

At this stage of database development, you can see inaccuracies in the names of attributes, their identity and specify the correct names, so that in subsequent modeling and normalization correctly interpret the attributes in question and correctly perform the necessary operations.

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