--自動(dòng)編號(hào)：Oracle
建表
create table t1(autoid number(10) primary key,name char(4));
創(chuàng)建序列
create sequence seq_t1_autoid;
添加數(shù)據(jù)
insert into t1(autoid,name) values(seq_t1_autoid.nextval,'a');
insert into t1(autoid,name) values(seq_t1_autoid.nextVal,'b');
commit;
--思考：能不能實(shí)現(xiàn)一個(gè)與DBMS無(wú)關(guān)的自動(dòng)編號(hào)方法?
insert into t1(autoid,name) select max(autoid)+1,'c' from t1;
insert into t1(autoid,name)??select max(autoid)+1,'d' from t1;
commit;
--改正：
insert into t1(autoid,name) select nvl(max(autoid),0)+1,'c' from t1;
insert into t1(autoid,name)??select nvl(max(autoid),0)+1,'d' from t1;
commit;

面試：如何在Oracle中實(shí)現(xiàn)與Mysql一樣的自動(dòng)編號(hào)：
解決：使用觸發(fā)器

create table t1(autoid number(10) primary key);
create sequence seq_t1_autoid;
create or replace trigger tr_t1_autoid
before insert on Friend
for each row
begin
??select seq_t1_autoid.nextval into :new.autoid from dual;
end;
--測(cè)試：
insert into t1(name) values('a');
insert into t1(name) values('b');
commit;
select * from t1;?

autoid? name??
?????1?? ? ?a????
?????2????? b????
+--------+------+