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This article mainly introduces "what is the basic concept of the database". In the daily operation, I believe that many people have doubts about the basic concept of the database. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "what is the basic concept of the database?" Next, please follow the editor to study!

The necessity of using databases

The use of database can store data efficiently and clearly, so that people can manage data more quickly and conveniently. The database has the following characteristics:

(1) A large amount of data and information can be stored structurally, which is convenient for users to retrieve and access effectively.

(2) it can effectively maintain the consistency and integrity of data information and reduce data redundancy.

(3) it can meet the sharing and security requirements of the application.

The basic concept of database

(1) data sheet

Symbolic records that describe things are called Data. The data includes numbers, words, graphics, images, sounds and so on.

In the database, the data is stored in a unified format in the form of "records", and the data of the same format and type are stored together to form a Table. Each row in the table is called a record and is used to describe the information of an object; each column is called a field and is used to describe the properties of an object.

(2) Database

Database (Database,DB) can be said to be a collection of tables, which is a collection of related data stored in a certain organizational way, with minimum redundancy and high data independence, which can be shared by all kinds of users.

(3) Primary key and foreign key

Primary key: each row of records in the data table is unique, and identical records are not allowed. The uniqueness of the record can be guaranteed by defining the primary key (primary key, Primary Key). The primary key consists of one or more fields whose values are unique and do not allow null values (NULL). A table can have only one primary key

Foreign keys: a database usually consists of multiple tables, which can be associated with foreign keys (Foreign Key)

(4) data integrity

Data integrity refers to the accuracy and reliability of the data. It is proposed to prevent the existence of data that does not conform to the semantic provisions in the database to prevent invalid operations or error messages caused by the input / output of error information. It is divided into the following four categories:

1) entity integrity: requires that the attribute of the primary key cannot have a null value, which forces the integrity of the primary key in the table. As shown in the figure above, each student has a number that uniquely represents the student's information, which is generally set as the student's primary key, so according to the entity integrity rules, the number cannot be empty.

2) Domain integrity: also column integrity, specifying the validity of a specific column. As shown in the figure above, the "gender" field can only take values of "male" and "female", so that invalid values are not entered.

3) referential integrity: if two tables are associated, it is required that tuples that do not exist are not allowed to be referenced and constrained by foreign keys

4) user-defined integrity: determined by the application environment, the constraints of a specific data are defined, and the semantic requirements of the data involved must be met.

(5) Database Management system (DBMS)

Database management system (Database Management System,DBMS) is a system software that realizes the effective organization, management and access of database resources. With the support of the operating system, it supports users' operations on the database.

(6) Database system (DBS)

Database system (Database System,DBMS) is a man-machine system, which consists of hardware, operating system, database, DBMS, application software and database users (including database administrators). Users can operate the database through DBMS or database application software

(7) Database Administrator (DBA)

The database administrator (Database Administrator,DBA) is responsible for the update and backup of the database, the maintenance of the database system and user management to ensure the normal operation of the database system.

An introduction to today's mainstream databases

Today, with the increasing development of databases, mainstream databases represent mature database technology. if we understand the commonly used databases, we can know the degree of development of database technology and the direction of development in the future.

SQL Server

Microsoft products for Windows operating system simple, easy to use Oracle Oracle products for all mainstream platforms security, improvement, operation complex DB2IBM products for all mainstream platforms large, security, perfect My SQL Oracle acquisition of Linux operating system open source, small, fast, stable to this, on the "what is the basic concept of database" learning is over, hoping to solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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