Create Trigger to Automatically Generate Primary Key

It is possible to automatically generate a primary key for Oracle Database tables when they are created. The steps below will show how to configure database tables so that primary keys are automatically generated:

The following example would create an automatic primary key generation with the following table:

1. Create Table with primary key and any additional attributes.
   create table test (id number, testdata varchar2(255));
2. Create Sequence
   create sequence test_seq
   start with 1
   increment by 1
   nomaxvalue;
3. Create Trigger
   create trigger test_trigger
   before insert on test
   for each row
   begin
   select test_seq.nextval into :new.id from dual;
   end;
   /
4. Test
   insert into test values(‘hello world!’);
   commit;
   select * from test;