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Computer textual research knowledge points

2022-01-26 22:06:06 Research on Maomao 475

One 、 Computer information system

1、 Understand the basic concepts of database

① data : Physical symbol sequence , Its content is the reflection of the characteristics of things .

database (DB): It is a general set of relevant data . It includes not only the data itself , It also includes links between data .

Database management system (DBMS): Is the core part of the database system , It's system software .

Database system (DBS): It refers to the system composition after introducing database into computer system . Include : hardware system 、 Database collection 、 Database management system and related software 、 Database administrator (DBA)、 The user etc. .

The basic concept of database application system :P268- The composition of the database (1)--(5)

② The development of database management technology :1、 Manual management stage ;2、 File system phase ;3、 Database system phase ;4、 Distributed database system stage .

③ Characteristics of database system (P267 Bottom row start ):1、 Implement data sharing , Reduce data redundancy ;2、 Adopt a specific data model ;3、 The data has high independence ;4、 With unified data control function

2、 Understand the data model

① The concept of database model : Is the organization form of database , At least by the data structure 、 Data operation and integrity are three parts .( See workbook P79)

② Three main data models : Hierarchical 、 Reticular type 、 Relational type . There are also “ Object oriented ”.

③ Relational database model and its characteristics : Relational database model is a data model that represents the relationship between entities in the form of two-dimensional tables . Its characteristics are :1、 Relationships must be standardized ;2、 Single model concept ;3、 Set operations

3、 Understand the database system schema

① Data independence : Refers to physical data independence and logical data independence .

② Database three-level mode ( structure ): Logical structure of user data 、 The overall logical structure of the data 、 The physical storage structure of data .

③ Generally master relational database 、 surface ( Two-dimensional table 、 attribute 、 Domain 、 keyword )?? P272 Basic terminology

Relational databases are built in relational models , Projection 、 Connect 、 Select three relationship operations .

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