You can't leave me, I can't live Without You

Data is the same as the air that surrounds us in our lives. Then, we need to use a warehouse to store the data in it. Therefore, our great predecessors invented the "database"! This is a great invention.

The need to use a database: The database can be efficiently and well-defined to store data, which enables people to manage data more quickly and easily.

The main embodiment: (1) can be structured to store a large amount of data information, convenient for users to effectively search and access. The database can classify the data and can provide fast queries.

(2) can effectively maintain the consistency of data information, integrity, reduce data redundancy. The data stored in the database can be used to ensure that the data is valid and not destroyed, and the database itself has the function of avoiding data duplication to reduce the redundancy of the data.

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

(4) database technology can be easily and intelligently analyzed to generate new useful information.

Here's a brief introduction to the database we use today:

(1) Introduction to SQL Server: SQL Server is a Microsoft company database product, and Microsoft SQL Server originates from Sybase SQL Server.

(2) Business Edition (SQL Server Enterprise Edition)

(3) Standard Edition (SQL Server Edition)

(4) Development Board (SQL Server Developer Edition)

(5) Free version (SQL Server Express)

Oracle Profile: Oracle is a database product for Oracle (Oracle) Corporation.

DB2 Introduction: DB2 with SYSTEMR as a prototype.　　　　The DB2 supports SMB to mainframe, but the best operating environment on the DB2 server side is IBM's own operating system platform os/400. DB2 database Core is also known as DB2 General Server, not only can run a variety of operating systems, and it is based on the corresponding platform environment has been adjusted and optimized to achieve better performance.

MySQL Introduction: MySQL is an open source relational database management system (RDBMS), because MySQL is open source, so anyone can download it under general Public License and modify it according to their individual needs.

Basic concepts of the database

(1) Entities and records

Entity: When describing an entity, it is for the "characteristics" of those entities.

Different data represent different entities.

Data in a database is stored in this format, rather than in a cluttered, uniform format and type of data.

Record: A data table of data stores, in which each row (row) actually corresponds to an entity, usually called a "record" in a database.

Database and Database tables

Database: A database is a collection of tables, logically the database includes data tables, tables that store relationships between tables, and various relational objects.

The database does not simply store the data for these entities, it also requires that the relationships between entities be expressed.

You can't leave me, I can't live Without You