用tirgger实现主键自增(trigger+sequence)
2015-11-27 08:59
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用tirgger实现主键自增:
create table book
(bid number(4) primary key,
bname varchar2(20)
)
create sequence book_seq
start with 1 --默认值
increment by 1; --增长率
create or replace trigger add_book_tri
before insert --insert前触发执行
on book
for each row --行级操作,每操作成功一行,触发一次
begin
if :new.bid is null then --如果没有插入主键值,则去序列中取值
select book_seq.NEXTVAL into :new.bid from dual;
end if;
end add_book_tri;
insert into book(bname) values ('Oracle');
create table book
(bid number(4) primary key,
bname varchar2(20)
)
create sequence book_seq
start with 1 --默认值
increment by 1; --增长率
create or replace trigger add_book_tri
before insert --insert前触发执行
on book
for each row --行级操作,每操作成功一行,触发一次
begin
if :new.bid is null then --如果没有插入主键值,则去序列中取值
select book_seq.NEXTVAL into :new.bid from dual;
end if;
end add_book_tri;
insert into book(bname) values ('Oracle');
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