Basic components of database system

The composition of the database system is as shown.

　 1) Hardware

The hardware of the database system includes the computer's host, keyboard, monitor, and peripherals (such as printers , optical drives, tape drives, etc.). Because of the large amount of data stored and processed in the general database system, and the rich function software of DBMS, the storage space occupied by it is very large, so the whole database system puts forward higher requirements for the hardware resources. These requirements are: The ① has enough memory to hold the operating system, the DBMS core module, the data buffer and the application, the ② has the big enough direct access device to hold the data (such as the disk), has the sufficient storage device to carry on the data backup , ③ requires the computer to have the high data transmission ability, To improve data transfer rates.

　 2) Software

Besides the database management system, the software of database system includes various advanced language processing programs (compiling or interpreting program), Application development tool software and specific application software. Application development tools include the Application Builder and the fourth generation language, such as efficient, multi-functional software tools, such as report generation system, tabular software, graphic editing system. They provide strong support for application developers and end users of database systems. Specific application software refers to the development of database applications for specific users, such as various database-based management software, management Information System (MIS), decision Support System (DSS) and office automation (OA) and so on.

　 3) data

Data is the basic composition of the database, is a representation of things in the objective world, but also the object of database users. Data is a database system, but also the real wealth of the enterprise or organization. Data should be collected in accordance with the requirements and have a structured database of stored persons. Because of the diversity of data types, data collection and storage methods will be different. Data as a resource is the most stable component of the database system, that is, the hardware may be updated, even the software can be updated, but as long as the nature of the enterprise or organization does not change, the data will be long-term use of wealth. The data in the database has the same set, share, minimum redundancy, and features that can serve a variety of applications as previously described.

　　 4) User

A database user is the principal that manages, develops, and uses a database. Depending on the work task, database users can typically be divided into 3 different types, including end users, application programmers, and database administrators.

(1) End user

The end user accesses and applies the data in the database using the Terminal command language provided by the database system, or by means of dialog such as menu-driven, table-driven, graphical display, and report generation. Such personnel are managers at all levels who are not proficient in computer and program design, but must receive the necessary training in database applications.

　 (2) Application programmer

The application programmer is the person responsible for designing and compiling the application. They typically use C, database language, or 4GL (fourth generation language) to design and write applications for end users. Application programmers not only require a high degree of technical expertise, but also have a deeper seniority, familiar with the nature and use of all the data in the Department, as well as the ability of system programmers, system analysts. Its specific responsibilities are: ① determine the content and structure of the database; ② determines the storage structure and access strategy of the database, makes the storage space utilization and access efficiency of the data better, ③ defines the security requirements and the integrity constraints of the data, ④ designs and compiles various powerful applications according to the needs of the end user.

For an application programmer, two important tools are required, one is a series of utilities (DBMS assembly, reorganization log, recovery, statistics, and so on), and the other is a data dictionary (information that stores the definition of a database structure, record types, and field definitions). When the database system is established, the DBA must also work with the system analyst to apply the system's requirements analysis and specification instructions, determine the system's hardware and software configuration and participate in the database design.

　 (3) Database administrator

A database administrator (data basead ministrator,dba) is a person who is fully responsible for the daily management, maintenance, and operation of the database system. The DBA is between the end user and the application programmer, is the database system is able to function the key, the large database system needs to set up the specialized management office. Its responsibility is to supervise the use and operation of the database, implement the maintenance, improvement and reorganization of the database system, and carry out the information socialization service.

For different sizes of database systems, the user's staffing is not the same. Only large database systems are equipped with application and database administrators. The application-based microcomputer database system is simple, the user usually has the function of end user and database administrator, but should also have the ability of application programmer when necessary.

Basic components of database system