列Oracle中设置自增列的简易操作(oracle中设置自增)
Oracle中通过 Sequence 和 Trigger可以实现自增列,以下内容将针对两种实现方式进行详细介绍,并结合具体代码给出示例。
## Sequence
Oracle提供了序列(Sequence)类型�为了实现自增列,可以使用Sequence来实现,以下为Oracle Sequence使用示例:
CREATE SEQUENCE seq_student
START WITH 1INCREMENT BY 1
NOMAXVALUENOCYCLE
NOCACHE;
CREATE TABLE student (id NUMBER PRIMARY KEY,
name VARCHAR2(20));
INSERT INTO student SELECT seq_student.nextval, 'Alice' FROM DUAL;
INSERT INTO student SELECT seq_student.nextval, 'Bob' FROM DUAL;
SELECT * FROM student;
-- Result-- ID NAME
-- 1 Alice -- 2 Bob
## Trigger
使用Trigger可以确保当表中插入记录时,自动为该条记录设置主键值。创建Trigger的步骤如下:
1. 创建Sequence
CREATE SEQUENCE seq_student
START WITH 1INCREMENT BY 1
NOMAXVALUENOCYCLE
NOCACHE;
2. 创建Table
CREATE TABLE student
(id NUMBER PRIMARY KEY,name VARCHAR2(20));
3.创建Trigger
CREATE OR REPLACE TRIGGER trigger_student
BEFORE INSERT ON student
FOR EACH ROWBEGIN
SELECT seq_student.nextval INTO: new.id
FROM dual;END;
/
4. 插入数据
INSERT INTO student
(name) VALUES ('Alice');
INSERT INTO student (name) VALUES ('Bob');
SELECT * FROM student;
-- Result-- ID NAME
-- 1 Alice -- 2 Bob
使用Oracle Sequence和Trigger可以实现自增主键。实现自增键以Sequence为主,在不传入主键值的情况下,Trigger可作为Sequence的扩展,以提升应用安全性。