select * from user_objects where object_type='TABLE';

--删除contact表,包括删除与其相关的约束

drop table contact cascade constraints

--创建contact表

create table contact(

id number(6) not null primary key

,first_name varchar2(20) not null

,last_name varchar2(20) not null

,birth_date Date

--,constraint pk_contact primary key(id) --指定主主键

);

drop sequence contact_seq;

--创建表contact的自增序列

create sequence contact_seq

start with 1

increment by 1

nomaxvalue

nocycle

nocache

drop trigger contact_trigger

--创建表contact自增序列的触发器

create or replace trigger contact_trigger

before insert on contact

for each row

begin

select contact_seq.nextval into:new.id from sys.dual;

end;

insert into contact(first_name,last_name,birth_date) values('Clarence','Ho',to_date('1980-07-30','yyyy-mm-dd'));

insert into contact(first_name,last_name,birth_date) values('Scott','Tiger',to_date('1990-11-02','yyyy-mm-dd'));

insert into contact(first_name,last_name,birth_date) values('John','Smith',to_date('1964-02-28','yyyy-mm-dd'));

--删除contact_tel表

drop table contact_tel cascade constraints;

--创建contact_tel表

create table contact_tel(

id number(6) not null primary key

,contact_id number(6) not null

--,contact_id number not null references contact(id)

,tel_type varchar2(20) not null

,tel_number varchar2(20) not null

--,constraint pk_contact_tel primary key(id) --主键

,constraint fk_contact_tel foreign key(contact_id) references contact(id) --外键

);

drop sequence contact_tel_seq;

--创建表contact_tel的自增序列

create sequence contact_tel_seq

increment by 1

start with 1

nomaxvalue

nocycle

nocache

drop trigger contact_tel_trigger

--创建表contact_tel自增序列的触发器

create or replace trigger contact_tel_trigger

before insert on contact_tel

for each row

begin

select contact_tel_seq.nextval into:new.id from dual;

end;

insert into contact_tel(contact_id,tel_type,tel_number) values (1,'Mobile','1234567890');

insert into contact_tel(contact_id,tel_type,tel_number) values (1,'Home','2234567890');

insert into contact_tel(contact_id,tel_type,tel_number) values (2,'Home','3234567890');

--以下测试主从表的外键约束是否生效

insert into contact_tel(contact_id,tel_type,tel_number) values (4,'Home','4234567890');

select * from contact;

select * from contact_tel;