SQL (Structured Query Language): Structured query language, a programming language for operating relational databases, defines a unified standard for operating all relational databases.

2.2 Common relational database management systems

Oracle: A large database for a fee.
MySQL: Open source and free small and medium-sized database. Later, Sun acquired MySQL, and Sun was acquired by Oracle.
SQL Server: A medium-sized database charged by Microsoft. C#, net and other languages are commonly used.
PostgreSQL: Open source free small and medium database.
DB2: IBM's large-scale fee-based database product.
SQLite: Embedded micro-database. Can be used as Andtoid built-in database.
MariaDB: Open source free small and medium database.

2.3 MySQL database

2.3.1. MySQL download

下载地址：MySQL :: Download MySQL Community Server (Archived Versions)MySQL :: Download MySQL Community Server (Archived Versions)
Select version: 5.7.24
Download the installation package
decompress
Contents of folders in MySQL

2.3.2MySQL configuration

1. Add environment variables

Right-click the Windows icon at the bottom left of the computer, click "System", click "Advanced System Settings", and click "Environmental Scalar" in the pop-up dialog box

2. Create a new system variable

3. Create a new path

4. Create a new configuration file

2.3.3 MySQL initialization

2.3.4 Start the MySQL service

Start MySQL from the command line: net start mysql

2.3.5 Login to MySQL

"mysql -V" to verify whether mysql is installed

Then enter the password XXXX... (myself)

Exit: "exit", "quit"

"mysql -u username -p password -h the ip address of the mysql server to connect to (default: 127.0.0.1) -P port number (default: 3306)"

2.3.6 MySQL Uninstall

1. Terminate the mysql service: "net stop mysql", press Enter

2. Uninstall: "mysqld - remove mysql"

3. Finally delete the MySQL directory and related environment variables

MySQL database concept and installation

1. Basic concepts

What is Javaweb?

2. Database

2.1 Related concepts of database