Create Table Student( 
 id number(12) primary key, --通过序列和触发器实现id的自增 
 name varchar2(20) , 
 age number(3) , 
 sex number(1) 
) 

Create Sequence SEQ_STUDENT 
minvalue 1 
maxvalue 99999999999999999999 
start with 1   --从1开始 
increment by 1 --增量为1 
cache 0 
order; 

Create or Replace Trigger STUDENT_AUTOINCREMENT 
Before Insert on Student 
For Each Row 
When (NEW.ID IS NULL) 
Begin 
Select SEQ_STUDENT.NEXTVAL INTO :NEW.ID FROM DUAL; 
End; 

SELECT * FROM DAYSBFJ.DAYS_CARD_UPDATE3 order by id asc
--alter table DAYSBFJ.DAYS_CARD_UPDATE3 add source_Flag varchar2(2);
--create sequence DAYS_CARD_UPDATE2_SEQ_ID minvalue 1 maxvalue 999999999 start with 1;
--Update DAYSBFJ.DAYS_CARD_UPDATE2 set id = DAYS_CARD_UPDATE2_SEQ_ID.nextval;
--update DAYSBFJ.DAYS_CARD_UPDATE3 set SOURCE_FLAG = '2'

create table test1(name1 varchar2(40),city varchar2(40));

insert into test1 values('name1','nanjing');
insert into test1 values('name1','nanjing');
insert into test1 values('name2','nanjing1');
insert into test1 values('name3','nanjing2');
insert into test1 values('name4','nanjing3');
insert into test1 values('name5','nanjing4');
insert into test1 values('name6','nanjing5');
insert into test1 values('name7','nanjing6');
insert into test1 values('name8','nanjing7');
insert into test1 values('name9','nanjing8');
insert into test1 values('name10','nanjing9');
insert into test1 values('name10','nanjing9');
insert into test1 values('name12','nanjing11');
insert into test1 values('name13','nanjing12');
insert into test1 values('name14','nanjing13');
commit;

alter table TEST1 add id number(10);

create sequence SEQ_ID
 minvalue 1
 maxvalue 999999999
 start with 1;

Update test1 set id=seq_id.nextval;
commit;

alter table TEST1
 add constraint PK_TEST1 primary key (ID);
 
select ID,Name1,CITY from TEST1;