记录一下自己练习时写的SQL语句

CREATE TABLE student(
stdid varchar2(20) Not NULL,
math varchar2(20),
ariticle varchar2(20),
languages    varchar2(20),         
music varchar2(20),
sport varchar2(20),
total varchar2(20),
average varchar2(20),
step varchar2(20)
);

alter table student
add constraint std_id primary key(stdid);

create table out_school(
stdid  varchar2(20)  not null,
practice varchar2(20),
commont varchar2(20)
);

alter table out_school
add constraint out_stdid primary key(stdid);


insert into student(stdid ,math,ariticle ,languages,music ,sport,total ,average,step) values (90,90,90,90,90,90,90,90,'A');
insert into student(stdid ,math,ariticle ,languages,music ,sport,total ,average,step) values (91,91,91,91,91,91,91,91,'A');
insert into student(stdid ,math,ariticle ,languages,music ,sport,total ,average,step) values (85,85,85,85,85,85,85,85,'B');

当要修改一个字段为另外一个字段时：

alter table student rename column A to B;