Oracle12c:支持通过创建identity columen来实现创建自增列

oracle12c之前如果需要创建自增列必须要通过sequence+trigger来实现。但是oracle12c已经可以像mysql,sqlserver一样通过identity column来设置自增列了。

 Connected to Oracle Database 12c Enterprise Edition Release 12.1.0.1.0
 Connected as My@TEST

 SQL>
 SQL> create table tab_test2
   2  (
   3      id number(38) generated as identity (start with 1 increment by 1),
   4      name varchar2(30),
   5      constraint PK_tab_test2 primary key (id)
   6  );
 Table created

 SQL> insert into tab_test2(name)values('hello');
 1 row inserted

 SQL> select * from tab_test2;
                                      ID NAME
 --------------------------------------- ------------------------------
                                       1 hello

 SQL> insert into tab_test2(name)values('hello2');
 1 row inserted

 SQL> insert into tab_test2(name)values('hello3');
 1 row inserted

 SQL> select * from tab_test2;
                                      ID NAME
 --------------------------------------- ------------------------------
                                       1 hello
                                       2 hello2
                                       3 hello3

 SQL> drop table tab_test2;
 Table dropped

当然也支持12c之前的版本所采用的方案：sequence+trigger的方案

 SQL>
 SQL> create table t_test (id number,name varchar2(100));
 Table created
 SQL> create sequence t_test_sequence
   2  increment by 1
   3  minvalue 1
   4  nomaxvalue
   5  start with 1
   6  cache 20
   7  order;
 Sequence created
 SQL> create or replace trigger t_test_id
   2  before insert on t_test
   3  for each row
   4  begin
   5  select t_test_sequence.nextval into :new.id from dual;
   6  end;
   7  /
 Trigger created
 SQL> insert into t_test(name) values('hello1');
 1 row inserted
 SQL> insert into t_test(name) values('hello2');
 1 row inserted
 SQL> insert into t_test(name) values('hello3');
 1 row inserted

 SQL> select * from t_test;
         ID NAME
 ---------- --------------------------------------------------------------------------------
          1 hello1
          2 hello2
          3 hello3

 SQL> drop table t_test;
 Table dropped

 SQL> 

查阅文档：

http://www.xifenfei.com/2015/03/oracle-12c-%E6%96%B0%E7%89%B9%E6%80%A7identity-columns-%E5%AE%9E%E7%8E%B0oracle%E8%87%AA%E5%A2%9E%E9%95%BF%E5%88%97%E5%8A%9F%E8%83%BD.html