mysql8 常用命令

mysql -uroot -proot
exit

mysql -uroot -p
输入密文：root

mysql -hlocalhost -uroot -proot

create databse db1;
show databases;
create databse db1 if not exists;
create database db3 character set utf8mb4;
show create database db3;
alter database db3 default character set gbk;
drop database db3;
use db1;
create table student (id int, name varchar(255), birth date, gender char(1));
desc student;
show create table student;
create table student2 like student;
drop table student;
drop table if exits student;
alter table student add remark varchar(20);
desc student;
alter table student modify remark varchar(100); 
alter table student change remark intro varchar(200);  
alter table student drop intro;
rename table student to student1;
show create table student;
alter table student character set gkb; 

蠕虫复制：
create table student3 like student;
insert into student3 select * from student;
insert into student3(id,name) select id,name from student;

创建表：
create table user(
    id int primary auto_increment comment '主键',
    name varchar(10) not null unique comment '姓名',
    age int check (age > 0 && age < 120) comment '年龄',
    status char(1) default '1' comment '状态',
    gender char(1) comment '性别'
) comment '用户表'

添加外键：
alter table emp add contraint fk_emp_dept_id foreign key (dept_id) refrences dept(id);

删除外键：
alter table emp drop foreign key fk_emp_dept_id;