如何在Oracle上使用AUTO_INCREMENT创建id？

Answer 1

从Oracle11g开始，Oracle中就没有“auto_increment”或“identity”列。但是，您可以使用序列和触发器轻松地对其建模：

表定义：

CREATE TABLE departments (
  ID           NUMBER(10)    NOT NULL,
  DESCRIPTION  VARCHAR2(50)  NOT NULL);

ALTER TABLE departments ADD (
  CONSTRAINT dept_pk PRIMARY KEY (ID));

CREATE SEQUENCE dept_seq START WITH 1;

触发器定义：

CREATE OR REPLACE TRIGGER dept_bir 
BEFORE INSERT ON departments 
FOR EACH ROW

BEGIN
  SELECT dept_seq.NEXTVAL
  INTO   :new.id
  FROM   dual;
END;
/

create table t1 (
    c1 NUMBER GENERATED by default on null as IDENTITY,
    c2 VARCHAR2(10)
    );

create table t1 (
    c1 NUMBER GENERATED ALWAYS as IDENTITY(START with 1 INCREMENT by 1),
    c2 VARCHAR2(10)
    );

CREATE SEQUENCE dept_seq START WITH 1;

CREATE TABLE departments (
  ID           NUMBER(10)    DEFAULT dept_seq.nextval NOT NULL,
  DESCRIPTION  VARCHAR2(50)  NOT NULL);

ALTER TABLE departments ADD (
  CONSTRAINT dept_pk PRIMARY KEY (ID));