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

Posted 2020-09-22 yy

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。

 1 Connected to Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 
 2 Connected as My@TEST
 3 
 4 SQL> 
 5 SQL> create table tab_test2
 6   2  (
 7   3      id number(38) generated as identity (start with 1 increment by 1),
 8   4      name varchar2(30),
 9   5      constraint PK_tab_test2 primary key (id)
10   6  );
11 Table created
12 
13 SQL> insert into tab_test2(name)values(‘hello‘);
14 1 row inserted
15 
16 SQL> select * from tab_test2;
17                                      ID NAME
18 --------------------------------------- ------------------------------
19                                       1 hello
20 
21 SQL> insert into tab_test2(name)values(‘hello2‘);
22 1 row inserted
23 
24 SQL> insert into tab_test2(name)values(‘hello3‘);
25 1 row inserted
26 
27 SQL> select * from tab_test2;
28                                      ID NAME
29 --------------------------------------- ------------------------------
30                                       1 hello
31                                       2 hello2
32                                       3 hello3
33 
34 SQL> drop table tab_test2;
35 Table dropped

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

 1 SQL> 
 2 SQL> create table t_test (id number,name varchar2(100));
 3 Table created
 4 SQL> create sequence t_test_sequence
 5   2  increment by 1
 6   3  minvalue 1
 7   4  nomaxvalue
 8   5  start with 1
 9   6  cache 20
10   7  order;
11 Sequence created
12 SQL> create or replace trigger t_test_id
13   2  before insert on t_test
14   3  for each row
15   4  begin
16   5  select t_test_sequence.nextval into :new.id from dual;
17   6  end;
18   7  /
19 Trigger created
20 SQL> insert into t_test(name) values(‘hello1‘);
21 1 row inserted
22 SQL> insert into t_test(name) values(‘hello2‘);
23 1 row inserted
24 SQL> insert into t_test(name) values(‘hello3‘);
25 1 row inserted
26 
27 SQL> select * from t_test;
28         ID NAME
29 ---------- --------------------------------------------------------------------------------
30          1 hello1
31          2 hello2
32          3 hello3
33 
34 SQL> drop table t_test;
35 Table dropped
36 
37 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