create database db1 charset utf8;

# 查看当前创建的数据库

show create database db1;

# 查看所有的数据库

show databases;

alter database db1 charset gbk;

drop database db1;

use db1; #切换文件夹

select database(); #查看当前所在文件夹

create table t1(id int,name char);

#查看当前的这张t1表

show create table t1;

# 查看所有的表

show tables;

# 查看表的详细信息

desc t1;

# modify修改的意思

alter table t1 modify name char(6);

# 改变name为大写的NAME

alter table t1 change name NAMA char(7);

# 删除表

drop table t1;

# 插入一条数据，规定id，name数据leilei

insert t1(id,name) values(1,"mjj01"),(2,"mjj02"),(3,"mjj03");

select id from db1.t1;

select id,name from db1.t1;

select * from db1.t1; 

update db1.t1 set name='zhangsan';

update db1.t1 set name='alex' where id=2;

delete from t1;

delete from t1 where id=2;