1.Sequence+Trigger实现Oracle列自增
CREATE SEQUENCE 序列名
[INCREMENT BY n]
[START WITH n]
[{MAXVALUE/MINVALUE n|NOMAXVALUE}]
[{CYCLE|NOCYCLE}]
[{CACHE n|NOCACHE}];
创建测试表
sys@newtestCDB> CREATE TABLE TEST(
2 ID NUMBER (10) NOT NULL,
3 DESCRIPTION VARCHAR2 (50) NOT NULL,
4 CONSTRAINT test_pk PRIMARY KEY (ID)
5 );

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Table created.

Elapsed: 00:00:00.14
sys@newtestCDB> CREATE SEQUENCE test_seq;

Sequence created.

Elapsed: 00:00:00.02

Elapsed: 00:00:00.38
sys@newtestCDB> CREATE OR REPLACE TRIGGER test_before_insert
2 BEFORE INSERT ON test
3 FOR EACH ROW
4 BEGIN
5 SELECT test_seq.NEXTVAL INTO :new.id FROM dual;
6 END;
7 /

Trigger created.

Elapsed: 00:00:00.12
sys@newtestCDB> INSERT INTO TEST (DESCRIPTION) VALUES ('不指定ID');

1 row created.

Elapsed: 00:00:00.08
sys@newtestCDB> INSERT INTO TEST (ID, DESCRIPTION) VALUES (TEST_USER.DEPT_SEQ.NEXTVAL, '指定ID');
INSERT INTO TEST (ID, DESCRIPTION) VALUES (TEST_USER.DEPT_SEQ.NEXTVAL, '指定ID')
*
ERROR at line 1:
ORA-02289: sequence does not exist

Elapsed: 00:00:00.01
sys@newtestCDB> INSERT INTO TEST (ID, DESCRIPTION) VALUES (TEST_SEQ.NEXTVAL, '指定ID');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> SELECT * FROM TEST;

    ID DESCRIPTION

---

     1 不指定ID
     3 指定ID

Elapsed: 00:00:00.03
2.DEFAULT Values Using Sequences
sys@newtestCDB> INSERT INTO TEST (description) VALUES ('DESCRIPTION only');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> INSERT INTO TEST (id, description) VALUES (999, 'ID=999 and DESCRIPTION');

1 row created.

Elapsed: 00:00:00.00
sys@newtestCDB> INSERT INTO TEST (id, description) VALUES (NULL, 'ID=NULL and DESCRIPTION');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> SELECT * FROM test;

    ID DESCRIPTION

---

     4 DESCRIPTION only
   999 ID=999 and DESCRIPTION
       ID=NULL and DESCRIPTION
Elapsed: 00:00:00.02

sys@newtestCDB> CREATE TABLE TEST(
2 ID NUMBER (10) DEFAULT ON NULL test_seq.NEXTVAL,
3 DESCRIPTION VARCHAR2 (50) NOT NULL
4 );

Table created.

Elapsed: 00:00:00.02
sys@newtestCDB> INSERT INTO TEST (description) VALUES ('DESCRIPTION only');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> INSERT INTO TEST (id, description) VALUES (999, 'ID=999 and DESCRIPTION');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> INSERT INTO TEST (id, description) VALUES (NULL, 'ID=NULL and DESCRIPTION');

1 row created.

Elapsed: 00:00:00.01
sys@newtestCDB> SELECT * FROM test;

    ID DESCRIPTION

---

     5 DESCRIPTION only
   999 ID=999 and DESCRIPTION
     6 ID=NULL and DESCRIPTION

Elapsed: 00:00:00.02
3.看上一篇里面

当前题目：oracle列自增实现
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