Index 실습

▣ Sequence 개념

-순차적인 고유한 일련번호를 제공

-Sequence는 테이블과 독립적으로 생성

-테이블의 행에 사용될 Primary Key 값을 자동적으로 만드는 데에 사용 가능

▣ Sequence 문법

SQL> CREATE SEQUENCE name

[INCREMENT BY n]

[START WITH n]

[MAXVALUE n] [MINVALUE n]

▣ Sequence 실습

SQL> CREATE TABLE transaction

(tr_id int,tr_nm char(10));

SQL> CREATE SEQUENCE seq_tr_id;

SQL> INSERT INTO transaction VALUES(seq_tr_id.nextval, '고객1');

SQL> INSERT INTO transaction VALUES(seq_tr_id.nextval, '고객2');

SQL> SELECT * FROM transaction;

SQL> SELECT * FROM user_sequences;

SQL> DELETE FROM transaction WHERE tr_id=2;

SQL> INSERT INTO transaction VALUES(seq_tr_id.nextval, '고객3');

SQL> SELECT * FROM transaction;

SQL> SELECT * FROM user_sequences;

SQL> DROP SEQUENCE seq_tr_id;