创建数据库：create database test; 查看数据库：show databases; 使用数据库：use test; 查看当前使用的数据库：select database(); 删除数据库：drop database test;(慎用！！！！！！！！！！！！！！)
创建表:create table people(id int primary key auto_increment,name varchar(20) not null,age int(8) not null,brithday datetime);
查看表：show tables; 查看表结构：desc people;
向表中插入一列：alter table people add handsome bool; 查看表结构：desc people;
修改表中字段属性：alter table people modify age int(4); 查看表结构：desc people;
删除列：alter table people drop column handsome;
修改表名：rename table people to information; 查看表：show tables;
复制表：create table copy_information select * from information; 查看表：show tables;
向表中插入数据：insert into information values(1,’张三’,23,’1993-04-12’,True); 查看表中内容：select * from information;
向表中添加多条数据，查看表中内容：select * from information;
删除表中数据：delete from information where name = ‘李四’; 查看表中内容：select * from information;
修改表中数据内容：update information set name=’叶良成’ where name=’李三’; 查看表中内容：select * from information;
创建表时候添加默认注释 CREATE TABLE test( id int primary key auto_increment comment ‘主键自增’, name varchar(200) comment ‘姓名’, ) comment=’表注释’;
