Mysql database ----- common commands of database (based on database)

------------------------------------------------- My database version 8.0.28-------------------------------------------------

One          view the database ：show databases;

These four databases are MySQL The system provides .

1. information_schema  Some database object information in the main storage system . For example, user table information , Column information, etc .
2. mysql   It mainly stores the user authority information of the system .
3. performance_schema   It mainly stores the performance parameters of the database server .
4. sys   Metadata information of the main storage system .

Two          Create database

create database + Database name ;（ Database naming specification reference ： Database naming rules -- Universal _HouYing-CSDN Blog _ Database naming rules ）

create database Test01;

 

  Obviously, create a database test01 success (SQL Statements are case insensitive ).

        * Security version creates database （ Use when you don't know whether the database name is duplicate ）.

         *  create database if not exists test;

         *  1 warning representative test Already exist , Not created again .

3、 ... and         Delete database

drop database + Database name

drop database test;

  Looking at the database again, I found test The database was deleted .

      * If you delete a nonexistent database, an error will be reported

       * Here is a safe way to delete the database （ See the text to know the meaning ）

       * drop database if exists test;

Four         Use specific databases

use + Database name

use test;

  You can see The database has been switched .

Focus on Me, Continuous updating MySQl Knowledge of databases .