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SQL> create table scott.logon(
2 id number(4) not null primary key,
3 name varchar(10),
4 password varchar(20));

Table created

SQL> create sequence logon_sequence
2 increment by 1
3 start with 1
4 nomaxvalue
5 nocycle
6 cache 10;

Sequence created

SQL> create trigger logon_tg before insert on scott.logon
2 for each row
3 begin
4 select logon_sequence.nextval into:new.id from dual;
5 end;
6 commit;
7

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ÎÒ²âÊÔÁËһϣ¬³ýÁËcommit; ûÓÐÎÊÌâ
insert into logon(name) values('aaa');
insert into logon(name) values('aaa');
insert into logon(name) values('bbb');

select * from logon
/

ID NAME PASSWORD
----- ---------- --------------------
1 aaa
2 aaa
3 bbb

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ÒýÓÃ

ÎÒ²âÊÔÁËһϣ¬³ýÁËcommit; ûÓÐÎÊÌâ
insert into logon(name) values('aaa');
insert into logon(name) values('aaa');
insert into logon(name) values('bbb');

select * from logon
/

  ID NAME      PASSWORD
----- ---------- ------