When designing the database table, we found that Oracle does not have the setting of auto increment primary key. Google understands that Oracle itself does not support auto increment primary key, which needs to be implemented through sequence and trigger.
Create table student
Create Table Student(
ID number (12) primary key, -- self increment of ID through sequence and trigger
name varchar2(20) ,
age number(3) ,
sex number(1)
)Create sequence
Create Sequence SEQ_STUDENT
minvalue 1
maxvalue 99999999999999999999
Start with 1 -- start with 1
Increment by 1 -- increment by 1
cache 0
order;Create trigger trigger
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;
Note:
1: A sequence can be shared by multiple tables.
2: The sequence generated by a sequence shared by multiple tables is always continuous and does not restart.
3: If you no longer use the sequence, delete it.
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'
Another example:
Create a new table without a primary key
create table test1(name1 varchar2(40),city varchar2(40));
–Insert data
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;
–Add primary key ID
alter table TEST1 add id number(10);
–Set sequence to increase ID automatically
create sequence SEQ_ID
minvalue 1
maxvalue 999999999
start with 1;
–Set the value of ID to sequence
Update test1 set id=seq_id.nextval;
commit;
–Set ID as primary key
alter table TEST1
add constraint PK_TEST1 primary key (ID);
select ID,Name1,CITY from TEST1;