在甲骨文12c以后，你可以这样做，

CREATE TABLE MAPS
(
  MAP_ID INTEGER GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1) NOT NULL,
  MAP_NAME VARCHAR(24) NOT NULL,
  UNIQUE (MAP_ID, MAP_NAME)
);

在Oracle (Pre 12c)中。

-- create table
CREATE TABLE MAPS
(
  MAP_ID INTEGER NOT NULL ,
  MAP_NAME VARCHAR(24) NOT NULL,
  UNIQUE (MAP_ID, MAP_NAME)
);

-- create sequence
CREATE SEQUENCE MAPS_SEQ;

-- create tigger using the sequence
CREATE OR REPLACE TRIGGER MAPS_TRG 
BEFORE INSERT ON MAPS 
FOR EACH ROW
WHEN (new.MAP_ID IS NULL)
BEGIN
  SELECT MAPS_SEQ.NEXTVAL
  INTO   :new.MAP_ID
  FROM   dual;
END;
/

在甲骨文12c以后，你可以这样做，

CREATE TABLE MAPS
(
  MAP_ID INTEGER GENERATED ALWAYS AS IDENTITY (START WITH 1 INCREMENT BY 1) NOT NULL,
  MAP_NAME VARCHAR(24) NOT NULL,
  UNIQUE (MAP_ID, MAP_NAME)
);

在Oracle (Pre 12c)中。

-- create table
CREATE TABLE MAPS
(
  MAP_ID INTEGER NOT NULL ,
  MAP_NAME VARCHAR(24) NOT NULL,
  UNIQUE (MAP_ID, MAP_NAME)
);

-- create sequence
CREATE SEQUENCE MAPS_SEQ;

-- create tigger using the sequence
CREATE OR REPLACE TRIGGER MAPS_TRG 
BEFORE INSERT ON MAPS 
FOR EACH ROW
WHEN (new.MAP_ID IS NULL)
BEGIN
  SELECT MAPS_SEQ.NEXTVAL
  INTO   :new.MAP_ID
  FROM   dual;
END;
/

oracle在12c中有序列和标识列

http://www.oracle-base.com/articles/12c/identity-columns-in-oracle-12cr1.php#identity-columns

我发现了这个，但不确定rdb7是什么 http://www.oracle.com/technetwork/products/rdb/0307-identity-columns-128126.pdf

查询如何在oracle中创建自动增量。在下面的查询中，每当插入新行时，列值将自动递增

CREATE TABLE table1(
id RAW(16) NOT NULL ENABLE,
incrmnt NUMBER(10,0) GENERATED ALWAYS AS IDENTITY
MINVALUE 1 MAXVALUE 999999999999999999999999999 INCREMENT BY 1 START WITH 1 NOORDER NOCYCLE NOT NULL ENABLE,
CONSTRAINT PK_table1 PRIMARY KEY (id) ENABLE);

Oracle数据库12c引入了Identity，一个自动增量(系统生成)列。 在以前的数据库版本中(直到11g)，您通常通过创建Sequence和Trigger来实现Identity。 从12c开始，您可以创建自己的Table并定义必须作为Identity生成的列。

在Oracle 11g中没有“auto_increment”或“identity”列这样的东西。然而，你可以很容易地用一个序列和一个触发器来建模:

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;
/

更新:

IDENTITY列现在可以在Oracle 12c上使用:

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

或者指定起始值和增量值，同时防止任何插入标识列(GENERATED ALWAYS)(同样，仅适用于Oracle 12c+)

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

另外，Oracle 12也允许使用一个序列作为默认值:

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));