Oracle基本操作

1.创建表格

create table student(

sno char(10) not null primary key,
name varchar2(40) not null,
sex char(2) check(sex in('0','1')),
sage number check(sage>=0 and sage <=200),
dept char(4)
);

create table sc(
sno char(10) not null,
cno char(10) not null,
grand number check(grand>=0 and grand <=100),
primary key(sno,cno),
foreign key(sno) references student(sno) on delete cascade ,
foreign key(cno) references course(cno) on delete set null
)

create table course(

cno char(4) primary key ,
cname char(40)

);

2.修改表格

alter table student add sex char(1);#增加一列
alter table student modify   sex char(2);#修改列的数据大小
alter table student student rename column sex to Ssex;#重命名列
alter table student add unique(name);#name列取唯一值约束