The primary key ID for an existing table in the Oracle database is set to self-increment

Create a table

CREATE TABLE T_ (
USER_ID number NOT NULL primary key,
User_name VARCHAR2 (30),
Credits number,
User_password VARCHAR2 (32),
Last_visit date,
Last_ip VARCHAR2 (23)
)

2. Create a sequence for this table

Create sequence T_seq
MinValue 1
MaxValue 999999999999999999999999999
Start with 21
Increment by 1
Cache 20;

3. Create a Trigger

Create or replace trigger TTR
Before insert on t
For each row
Begin
Select T_seq.nextval into:new.id from dual;
End T_tr;

4. Test

INSERT into t_user values (null, ' xiaoming ', 123, ' 111 ', sysdate, ' 192.168.37.132 ');
INSERT into T_user values (6, ' xiaoming ', 124, ' 111 ', sysdate, ' 192.168.37.132 ');
SELECT * FROM T_user

The primary key ID for an existing table in the Oracle database is set to self-increment