Introduction:
Database management system is referred to as DBMS. It is the system software of the computer like the operating system and is also a large and complex software system. .
Main functions:
1. Data definition
DBMS provides data definition language (DDL), through which users can easily define the data in the database. Data objects are defined.
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2. Data organization, storage and management
DBMS must classify, store and manage various Data, including data dictionary, user data, data access paths, etc. It is necessary to determine what file structure and access method to store and organize these data, and how to realize the connection between the data.
The basic goal of data organization and storage is to provide multiple access methods to improve storage space utilization and facilitate access, such as using index search, hash search, etc. to improve access efficiency.
3. Data manipulation
DBMS also provides data manipulation language (DML). Users can use DML to manipulate data and implement basic operations on the database, such as query, insertion, deletion and modification.
4. Database transaction operation and operation management
When the database is established, used and maintained, it is managed and controlled uniformly by the database management system to ensure the security, integrity and multiplexing of the data. Concurrent use of data by users and system recovery after failure.
5. Database establishment and maintenance
Includes database initial data input and conversion functions, database dump and recovery functions, database reorganization functions and performance monitoring and analysis functions, etc. These functions are usually performed by some utilities or management tools.
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