Create auto increment field in Oracle database.

1. Create Table:

CREATE TABLE PERSON(

ID INT PRIMARY KEY,

FIRSTNAME VARCHAR2(20),

LASTNAME VARCHAR2(20)

)

2. Create Sequence:

CREATE SEQUENCE seq_person

MINVALUE 1

START WITH 1

INCREMENT BY 1

CACHE 10

3. Create Trigger, it will insert value for column "id" automatically:

CREATE OR REPLACE TRIGGER per_id

BEFORE INSERT ON person

FOR EACH ROW

BEGIN

  SELECT seq_person.NEXTVAL

  INTO   :new.id

  FROM   dual;

END;

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