----约束------- --1.主键约束--唯一标识,不能为空,通常用于ID--1>创建主键create table person(id varchar2(20) primary key,name varchar2(50),birthday date,sex varchar2(2) default '男');insert into person(id,name,birthday,sex)values(1,'zhangsan',to_date('1988-05-11','yyyy-mm-dd'…