The concept of a database

　　 definition 1:

Strictly speaking, databases are "warehouses that organize, store, and manage data according to data structures." In the daily work of economic management, it is often necessary to put some relevant data into such a "warehouse", and according to the needs of management to deal with accordingly. For example, the personnel departments of enterprises or institutions often have to put the basic situation of the staff of the Unit (employee number, name, age, sex, place of origin, salary, resume, etc.) in the table, this table can be considered as a database. With this "Data Warehouse" we can at any time to inquire about the basic situation of a worker, you can also query wages in a certain extent, the number of workers and so on. If all of this work can be done automatically on the computer, our personnel management can reach a very high level. In addition, in the financial management, warehouse management, production management also need to establish a large number of such "database", so that it can use the computer to achieve financial, warehouse, production automation management.

J.Martin gives the database a more complete definition: A database is a collection of related data that is stored together, structured, harmless, or unnecessarily redundant, and serves a variety of applications; data is stored independently of the program that uses it; Insert new data into the database. The original data can be modified and retrieved in a common and controllable manner. When there are several databases that are structurally separate on a system, the system contains a collection of databases.

　　Definition 2:

The database is organized according to some data model and holds the data collection in level two memory. This data set has the following characteristics: As far as possible without duplication, in the best way for a specific organization of a variety of applications, the data structure is independent of the application of its applications, the increase, deletion, modification and retrieval by the unified software management and control. From the history of development, database is the advanced stage of data management, it is developed by file management system.

　　Definition 3:

(views of the Committee of Experts on the Berne Convention Protocol) All information (data rate files) of the codification, whether in print form, computer storage unit form, or other forms of existence, should be considered as "database". There are many reasons for the selection of digital content, summed up mainly:

(1) The reason for storage space. Digital products are accessed and utilized by the vast number of users through the network, and we all know that digital products are stored on the disk array, the disk array by the server to manage, disk space is limited, the server's ability is limited, it is impossible to save unlimited number of digital resources, which requires us to select the digital content of literature resources.

(2) To solve the contradiction between the high cost of digital production and the limited funds of library. Few libraries have sufficient resources to digitize the entire collection, and the choice of content is unavoidable.

(3) The need of digital resource management. With the rapid development of technology, the life cycle of digital resources generated by digital projects is getting shorter, and the cost of digital migration is 1 important ways to prolong the life of digital resources, and the expensive maintenance costs must consider the choice of digital content.

Database history database technology from the birth to the present, in less than half a century, the formation of a solid theoretical foundation, mature commercial products and a wide range of applications, attracting more and more researchers to join. The birth and development of the database bring a great revolution to the computer information management. Over the past more than 30 years, tens of thousands of databases have been developed and built at home and abroad, which has become an infrastructure for the daily work, production and living of enterprises, departments and even individuals. At the same time, with the extension and deepening of the application, the number and scale of the database are more and more large, and the research field of database has been greatly broadened and deepened. The three Computer Turing Awards (C.W. bachman,e.f.codd, J.gray) were obtained in the database field in 30, more fully explaining that the database is a vibrant and innovative area. Let us follow the history of the track, retrospective database development process.

Traditionally, in order to ensure the continuous expansion of the enterprise IT system stable operation, the general user Information Center often not only to constantly update more capacity of IT operations and hardware and software equipment, a great waste of enterprise resources, but also long-term maintenance by the database maintenance, server maintenance, computer room on duty, such as a variety of maintenance personnel composed of The cost of maintenance is soaring. To this end, the enterprise IT decision makers began to think: can you like to screw the faucet on the need to adjust the use of IT operational services? Instead of increasing the already expensive operational costs.

　　Definition 4:

A database (DATABASE,DB) is a collection of organized, shared, and managed data that is stored on a computer for a long time. She is a computer software system that stores and manages data according to the structure. The concept of the database actually consists of two layers meaning:

(1) The database is an entity, it is able to reasonably keep the data "warehouse", the user in the "warehouse" storage to manage the transaction data, "Data" and "library" two concepts into a database.

(2) database is a new method of data management and technology, he can more suitable organization of data, more convenient maintenance data, tighter control data and more efficient use of data.