Self-increment implementation of oracle column
1.Sequence+Trigger implements self-increment of Oracle columns
CREATE SEQUENCE sequence name
[INCREMENT BY n]
[START WITH n]
[{MAXVALUE/MINVALUE n | NOMAXVALUE}]
[{CYCLE | NOCYCLE}]
[{CACHE n | NOCACHE}]
Create a test table
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)
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 ('do not specify ID')
1 row created.
Elapsed: 00:00:00.08
Sys@newtestCDB > INSERT INTO TEST (ID, DESCRIPTION) VALUES (TEST_USER.DEPT_SEQ.NEXTVAL, 'specify ID')
INSERT INTO TEST (ID, DESCRIPTION) VALUES (TEST_USER.DEPT_SEQ.NEXTVAL, 'specify 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, 'specify ID')
1 row created.
Elapsed: 00:00:00.01
Sys@newtestCDB > SELECT * FROM TEST
ID DESCRIPTION 1 does not specify ID 3 specify 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 DESCRIPTIONElapsed: 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. Look in the last article.
