Getting started with mysql is enough! ! (Continually updated)

mysql -uroot -p  //回车以后输入密码即可

Show the database directory

show databases;

As shown:
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information_scheam  //存的是视图
mysql//核心数据，存很多的表文件
performance_schema//对性能提升做操作的数据库   存的是表
//前三个尽量不动

Query the statements needed to create a database and view its character set

show create database mysql；

As shown in the figure:
Insert picture description here
you can see that the character set utf-8 is marked in the comment behind. It explains the encoding format of our database.

Create a database:

create database db1;//db1可以换成你想创建的任何数据库的名字

To avoid mistakes

create database if not exists db1;//我们可以在建表时看一下我们的名称是否重复，避免报错

When creating a new database, you can change its character set

create database db2 character set gbk;

Small exercise:
create a database db4, and check whether it exists in advance and change the character set to gbk

create database  if not exists db4 character set gbk;

Modify the character set of the database

alter database db4 character set utf8mb4;

Delete database

drop database if exists db4;//避免报错加上if语句

Use database

//查看当前使用的数据库
select database();
//使用数据库
use db1;//注意直接使用数据库名

Table operations
View the names of all tables in the database

show tables;

Structure of the lookup table

desc 表名;//desc 是描述的意思

Create table

 create table student(
     id int,
     name varchar(32),
     age int,
     score double(4,1),
     birthday date,
     insert_time timestamp
     );
     //前面是名称后面是类型
     timestamp是系统当前的时间

Copy table

create table 表名 like 基表;

Delete table

drop table if exists student;
或者直接
drop table;

Modify table

修改表名
alter table 表名 rename to 新表名;
修改表的字符集
alter table 表名 character set gbk;
添加一列
alter table 表名 add 列名 数据类型;
修改列名称，类型
alter table 表名 change 原列名 新列名 新类型;
若不改变名称只改变类型
alter table 表名 modify 原列名  新类型;
删除列
alter table stu drop sex;

DML: Add, delete and modify data in the table
1. Add data
insert into table name (column name 1, column name 2, …, column name n) values (value 1, value 2, …, value 3);
or
insert into table name values (Value 1, value 2, ..., value 3);

Getting started with mysql is enough! ! (Continually updated)

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