The concept of building a database
The concept assumes the statement of the main provisions of something. The description of the DB concept can not be performed without considering the chronology .
Engineering and economic tasks
Initially (the beginning of the 60s of the XX century) a file storage system was used. To solve mostly engineering problems, characterized by a small amount of data and a significant amount of calculations, the data was stored directly in the program. A consistent method of data organization was used, there was their high redundancy, the identity of the logical and physical structures, and the complete dependence of the data.
Fig. 2.1. Information retrieval system
With the advent of economic-management tasks (information management system - MIS), which are characterized by large amounts of data and a small fraction of calculations, this organization of data proved ineffective. The ordering of the data was required, which, as it turned out, could be carried out according to two criteria: use (information arrays); storage (database).
Information retrieval and information-advisory systems of management.
It should be noted  that economic tasks are often associated with the management of organizational systems. By the nature of the use of computers, such systems can be divided into information retrieval systems (Figure 2.1), also called "traditional", and information-advising or modern (Figure 2.2) systems. First there was a construction and studying of traditional systems.
Fig. 2.2. Information and advisory system
Information arrays and databases
Initially, in information retrieval systems used information arrays. At the same time, there was a need to store redundant information in the presence of computer memory deficits. It was also found out that the task algorithms are more mobile than the data for them. With fairly frequent changes in algorithms in the process of improving control systems, each time it was required to carry out a laborious procedure for creating new arrays. Under these conditions, the superiority of databases became clear, despite their more complex structure compared to the array system. Subsequently, databases began to be supplied with a software component that makes it easy to implement and quickly modify application algorithms.
Using files to store only the data (Figure 2.3, a ), McGry was suggested in 1959. Methods were developed for accessing (including arbitrary) such files, while the physical and logical structures already differed, and the physical arrangement of the data could be changed without changing the logical representation.
In 1963, S. Bachman built the first industrial IDS database with a network data model, which was still characterized by data redundancy and its use for only one application. Access to the data was carried out using the appropriate software.
Fig. 2.3. The file system ( a ) and the DBMS ( b ) for data storage
In 1969, a group formed a set of standards CODASYL (CODASYL) for the network data model. In fact, the modern architecture of the database was then used (Figure 2.3, b ). A significant leap in the development of database technology occurred in 1970, when M. Codd proposed the paradigm of the relational data model. The paradigm is understood as a scientific theory embodied in a system of concepts that reflect the essential features of reality. Now logical structures could be obtained from the same physical data, i.e., different applications could access the same physical data in different ways. It became possible to ensure the integrity and independence of the data.
In the late 70-ies of XX century. there are modern DBMS that provide physical and logical independence, data security, and have developed database languages.
In the early 1990s, relational databases became the most widely used, especially when using personal computers. There were various DBMS, calculated both for the professional user (in programming) and for the non-professional user, intended for building both small (in terms of memory) and super-large databases operating both in local and network modes. At the same time databases were built as static (in foreign terminology - operational, transactional, On Line Transactional Processing - OLTP).
By the mid-90s, databases had accumulated so much information that it became possible to use it for analytical procedures to develop solutions-councils. There are dynamic (analytical) databases, called overseas OnLine Analytical Processing - OLAP. Their main components are the electronic archive and data warehouse (Data Warehouse).
Simultaneously, shortcomings of relational databases were revealed, in which competitors appeared in the form of object-oriented databases.
The last decade is characterized by the emergence of distributed and object-oriented databases, the characteristics of which are determined by applications of design automation and database intelligence.
Before considering the procedures for working with the database, we will give a set of database characteristics and explanations to it.
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