Data
1. Data (Data) is the basic object stored in the database
2. Definition of data
Symbol records describing things
3. Types of data
Text, graphics, images, audio, video, student records, cargo transportation, etc.
4 .Characteristics of
data Data and its semantics are inseparable
Database
1. The definition of
database A database (DB, referred to as DB) is a collection of a large amount of organized and shared data stored in a computer for a long time.
2. The basic characteristics of the database
(1) Data is organized, described and stored according to a certain data model
(2) Can be shared by various users
(3) Redundancy is small
(4) Data independence is high
(5) Easy to expand
Database Management System
1. What is DBMS
(1) A layer of data management software located between the user and the operating system.
(2) It is the basic software, which is a large and complex software system.
2. The purpose of the DBMS.
Scientifically organize and store data, and efficiently obtain and maintain data.
3. The main functions of the DBMS.
(1) The data definition function
provides data definition language (DDL). )
Define the data objects in the database
(2) Data organization, storage and management.
Classification organization, storage and management of various data.
Determine the file structure and access methods of the organization data.
Realize the connection between data.
Provide multiple access methods to improve access. Efficiency
(3) Data manipulation function
Provide data manipulation language (DML) to
realize basic operations on the database (query, insert, delete and modify)
(4) Database transaction management and operation management The
database is unified by DBMS during establishment, operation and maintenance Management and control
Ensure data security, integrity, and concurrent use of data by multiple users
. System recovery after failure
(5) Database establishment and maintenance function (utility program)
Database initial data load conversion
Database dump
Media failure recovery
database Reorganization,
performance monitoring and analysis, etc.
(6)
Communication
between other functional DBMS and other software systems in the network Data conversion between two DBMS systems
Inter-access and interoperability between heterogeneous databases
Database system
1. What is the database system (DBS)
after introducing the database into the computer system?
2. The composition of the
database
system Database Database Management System (and its development tools)
Application System
Database Administrator
Data and information
Data is the carrier of
information Information is the connotation of data
Data classification
1. Formatted data: EXCEL form, XML; THML; file format; specially agreed format
2. Unformatted data: language, audio, video
Factors of converting data into information
1. If there is a clear semantic definition of data, there is no deviation in the conversion of data and information
2. If not, it depends on the following factors:
the tacit understanding between the data producer (information sender) and the data receiver (information understander); for example, the message is transmitted by picture or gesture;
3. The knowledge of the information understander Background, experience, etc.