SQL overview
SQL is the standard language for relational databases, and it is also a general-purpose, extremely powerful relational database language.
Its function is not only query, but includes a series of functions such as database schema creation, database insertion and modification, database security integrity definition and control.
Basic Concepts of SQL
The relational database management system that supports SQL also supports the three-level schema structure of the relational database
The outer schema includes several views and some basic tables
The schema includes several basic tables
Internal mode includes several storage files
MySQL database
Start the MySQL service
Login to MySQL
The first: in MySQL 8.0 Command Line Client - Unicode login
The second: log in with the DOS command in Windows:
1. Go to the bin folder in the MySQL directory
2. Enter mysql -hlocalhost -uroot -p
Common DOS command operations:
①cd\: return to the root directory of the disk ②cd..: return to the previous directory ③cd+file name: enter a file ④F: directly count into the F disk
The third type: login in the third-party graphical interface
Create and delete databases
The first: command line →create database database name; command line →drop database database name;
The second: third-party creation → new database, delete database