【正文】 retrieved by a mon and can be controlled manner. When a system in the structure of a number of entirely separate from the database, the system includes a database collection. Database management system (database management system) is a manipulation and largescale database management software is being used to set up, use and maintenance of the database, or dbms. Its unified database management and control so as to ensure database security and integrity. Dbms users access data in the database, the database administrator through dbms database maintenance work. It provides a variety of functions, allows multiple applications and users use different methods at the same time or different time to build, modify, and asked whether the database . It allows users to easily manipulate data definition and maintenance of data security and integrity, as well as the multiuser concurrency control and the restoration of the database. Using the database can bring many benefits: such as reducing data redundancy, thus saving the data storage space。 database management statement is in line with international standards, in line with international standards, the system is easy to maintain, development, transplantation。 the database capacity, capacity characteristic database determines the scope of use of the database management system. (2) the degree of difficulty of program development. There is no puter aided software engineering tool CASE puter aided software engineering tools can help developers to provide maintenance, coding environment in the development phase of the method according to software engineering, development, maintenance is convenient for plex software. A design method of the fourth generation language development with a non procedural language platform without the fourth generation language, the user does not need to write code to process plex, and easy to understand, easy maintenance. A logical way of non object oriented design platform the idea of objectoriented design is very similar to humans, to facilitate the development and maintenance. The multimedia data type support multimedia data needs is a development trend in the future, will be a database management system to support multimedia data types to reduce application development and maintenance. (3) performance analysis of database management system. Including evaluating performance (response time, throughput of data per unit time), performance monitoring (internal and external memory usage, system input / output rate, the SQL statement, the database tuples control), performance management (parameter setting and adjustment). (4) for distributed application support. Including data transparency and work transparency. Transparent data refers to the user does not need to point out what the data on the nodes in the work in the application, the database management system can automatically search the Inter, extract the required data。 horizontal expansion to meet the requirements of extended hardware, support from the single CPU model into CPU parallel machine model (SMP, CLUSTER, MPP) (7) data integrity constraints. Data integrity refers to the consistency and correctness of data protection, including the entity integrity, referential integrity, plex business rules. (8) concurrency control function. For the distributed database management system, concurrency control function is essential. Because it is facing the task distribution environment, there may be multiple users at the same time on the same data read or write operation, in order to ensure