『ORACLE』 约束实验（11g）

create table student 

(

   sno                  NUMBER(5)            not null,

   sname                VARCHAR2(20),

   idcard               VARCHAR2(18),

   createtime           DATE                 default SYSDATE,

   nno                  NUMBER(2),

   constraint PK_STUDENT primary key (sno)

);

create table course 

(

   cno                  NUMBER(5)            not null,

   cname                VARCHAR2(20),

   constraint PK_COURSE primary key (cno)

);

create table nativeplace 

(

   nno                  NUMBER(2)            not null,

   np_name              VARCHAR2(20),

   constraint PK_NATIVEPLACE primary key (nno)

);

create table sc 

(

   sno                  NUMBER(5)            not null,

   cno                  NUMBER(5)            not null,

   grade                NUMBER(4,1),

   constraint PK_SC primary key (sno, cno)

);

alter table sc add constraint fk_sc_sno foreign key (sno) references student (sno) on delete cascade;

alter table sc add constraint fk_sc_cno foreign key (cno) references course (cno);

alter table student add constraint fk_student foreign key (nno) references nativeplace (nno) on delete set null;

insert into nativeplace values(1,'heilongjiang');

insert into nativeplace values(2,'jilin');

insert into nativeplace values(3,'liaoning');

insert into nativeplace values(4,'beijing');

insert into course VALUES(1,'Oracle');

insert into course VALUES(2,'Java');

insert into course VALUES(3,'C++');

insert into student values(1,'zhangsan','123456789123456780',default,1);

insert into student values(2,'lisi','123456789123456781',default,2);

insert into student values(3,'wangwu','123456789123456782',default,3);

insert into student values(4,'zhaoliu','123456789123456783',default,4);

insert into sc values(1,1,91);

insert into sc values(1,2,92);

insert into sc values(1,3,93);

insert into sc values(2,1,88);

insert into sc values(2,2,77);

insert into sc values(2,3,99);

insert into sc values(3,1,65);

insert into sc values(3,2,75);

insert into sc values(3,3,85);

insert into sc values(4,1,80);

insert into sc values(4,2,88);

insert into sc values(4,3,89);

commit;

alter table sc drop constraint fk_sc_sno;

alter table sc drop constraint fk_sc_cno;

alter table student drop constraint fk_student;

drop table course cascade constraints;

drop table nativeplace cascade constraints;

drop table sc cascade constraints;

drop table student cascade constraints;