编辑代码

CREATE DATABASE r7;
use r7;
CREATE TABLE student(id int,name char(10),age int(4),sex VARCHAR(2));
alter table student modify id int primary key auto_increment;
alter table student modify name char(10) not null;
alter table student modify age int(4) default '18';
alter table student modify sex VARCHAR(2) default '男';
describe student;
insert into student values(1,'张三',18,'男'),(2,'李四',20,'女'),(3,'王五',21,'女');
update student set age=200 where name='李四';
update student set age=300 where sex='男';


CREATE DATABASE r7;
use r7;
CREATE TABLE student(id int,name char(10),age int(4),sex VARCHAR(2));
alter table student modify id int primary key auto_increment;
alter table student modify name char(10) not null;
alter table student modify age int(4) default '18';
alter table student modify sex VARCHAR(2) default '男';
describe student;
insert into student values(1,'张三',18,'男'),(2,'李四',20,'女'),(3,'王五',21,'女');
update student set age=200 where name='李四';
update student set age=300 where sex='男';