Oracle self-Increment ID implementation

First, create a table:

CREATE TABLE Example (

ID Number (4) Not NULL PRIMARY KEY,

NAME VARCHAR (25));

Then, customize a sequence (sequence):

CREATE SEQUENCE example_sequence

INCREMENT by 1--add a few each time

Start with 1-counting starting from 1

Nomaxvalue--Do not set the maximum value

Nocycle--keep accumulating, not looping

NOCACHE--Do not build buffers

Create a second trigger:

CREATE TRIGGER Example_triger before

INSERT on example for each ROW time (new.id is null)-- starts the trigger generation ID number only when the ID is empty

Begin

Select Example_sequence.nextval into:new.id from dual;

End

Test it, insert the data

Insert into example (name) VALUES (' Zhang San ');

Insert into example (ID, name) VALUES (111, ' John Doe ');

Input query statement:

Select t.* from EXAMPLE t

The result is:

Id	Name
1	Tom
111	John doe

Oracle self-Increment ID implementation