How Oracle builds a self-increment field on a table

This method for using sequence (sequence) For example has a table temp_test structure for: CREATE TABLE Temp_test
(
ID number,
NM varchar (10),
Primary key (ID)//ID is the primary key, and the following method sets it as the self-increment field
1, establish the self-increment sequence temp_test_idadd, name any, starting from 1, each add 1CREATE SEQUENCE temp_test_idadd INCREMENT by 1 start with 1; 2, in table temp_t Create a trigger on est as follows create OR REPLACE TRIGGER t_temp_test_idadd
Before INSERT on Temp_test
For each ROW
BEGIN
SELECT Temp_test_idadd. Nextval INTO:NEW.ID from DUAL;
END T_temp_test_idadd; Test results: Add data to the Temp_test table and execute the following statement two times insert into temp_test (NM)
VALUES (' SS '); The results are as follows:

How Oracle builds a self-increment field on a table