oracle的自增長

mysql的自增長非常容易，一個 AUTO_INCREMENT

就搞定，可是oracle就不行了

下面是oracle的自增長

#創建一個表
CREATE TABLE T_TEST_DEPARTMENTS (
ID NUMBER (10) NOT NULL,
DESCRIPTION VARCHAR2 (50) NOT NULL
);

#創建一個表
CREATE TABLE T_TEST_DEPARTMENTS2 (
ID NUMBER (10) NOT NULL,
DESCRIPTION VARCHAR2 (50) NOT NULL
);
#設置唯一的字段
ALTER TABLE T_TEST_DEPARTMENTS ADD (CONSTRAINT) dept_pk PRIMARY KEY (ID);
ALTER TABLE T_TEST_DEPARTMENTS2 ADD (CONSTRAINT dept_pk PRIMARY KEY (ID));
#創建序列
CREATE SEQUENCE dept_seq;
CREATE SEQUENCE dept_seq2;
#觸發器版本1:非空時，才使用序列的NEXTVAL值
CREATE OR REPLACE TRIGGER dept_before_insert 
BEFORE INSERT ON T_TEST_DEPARTMENTS 
FOR EACH ROW
WHEN (NEW.ID IS NULL)
BEGIN
SELECT dept_seq.NEXTVAL INTO :NEW.ID FROM dual ;
END ;
觸發器版本2: 無視插入數據時，指定的ID
CREATE OR REPLACE TRIGGER dept_before_insert2
BEFORE INSERT ON T_TEST_DEPARTMENTS2 
FOR EACH ROW
BEGIN
SELECT dept_seq2.NEXTVAL INTO :new.id FROM dual;
END;
#測試數據
INSERT INTO T_TEST_DEPARTMENTS (ID, DESCRIPTION) VALUES (19, '指定ID');
INSERT INTO T_TEST_DEPARTMENTS (DESCRIPTION) VALUES ('不指定ID');

INSERT INTO T_TEST_DEPARTMENTS2 (ID, DESCRIPTION) VALUES (19, '指定ID');
INSERT INTO T_TEST_DEPARTMENTS2 (DESCRIPTION) VALUES ('不指定ID');

 

參考轉載自：http://www.cnblogs.com/xqzt/p/4452292.html