But with oracle database 12c this concept is changed new features add when you create table called generated as identity.
Check the Below Demonstration which explain this new features :
SQL> create table test (test_id number generated as identity , test_name varchar2(20));
SQL> desc test ;
Name Null? Type
—————————————– ——– ————–
TEST_ID NOT NULL NUMBER
TEST_NAME VARCHAR2(20)
SQL> insert into test values (1,’osama’);
insert into test values (1,’osama’)
*
ERROR at line 1:
ORA-32795: cannot insert into a generated always identity column
The TEST_ID Column will be inserting automatically no need to use in insert command.
SQL> insert into test (TEST_NAME) values ( ‘Jennifer’ );
1 row created.
SQL> select * from test ;
TEST_ID TEST_NAME
———- ——————–
1 Jennifer
SQL> create table test2 (TEST_ID NUMBER generated as identity (start with 1 increment by 1 cache 30 order), TEST_NAME varchar2(20));
Table created.
SQL> insert into test2 (test_name) values (‘JENNIFER’);
SQL> insert into test2 (test_name) values (‘STEVE’);
SQL> insert into test2 (test_name) values (‘USER’);
SQL> select * from test2 ;
TEST_ID TEST_NAME
———- ——————–
1 JENNIFER
2 STEVE
3 USER
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