student.txt

oracle操作基础基础基础基础基础基础基础基础基础基础基础基础

create table student (
sno varchar2(10) primary key,
name varchar2(20) not null unique,
sex varchar2(2) check(sex in('男','女')),
age number(2) check(age between 16 and 20),
class varchar2(7) not null)