Several confusing concepts of MySQL

1. MySQL database service: it is the general name of MySQL software, MySQL instance and MySQL database, sometimes referred to as MySQL service.

2. MySQL instance: refers to the mysqld process

3. MySQL database: a collection of at least 4 physical files in the MySQL data directory (test, mysql, information_schema, performance_schema)

4. Mysql database: refers to a specific library in the MySQL database named mysql, referred to as the mysql library

5. Mysql command: generally refers to the mysql command in the bin directory where the files are installed

6. Mysql operating system user: generally, an operating system user mysql is automatically created during rpm installation.

7. Mysql database user the superuser of root:mysql database is root by default, which has nothing to do with the root of Linux operating system.