How to Create Auto Increment Column in Oracle

Oracle hasn't got a Auto Increment feature by default as SQL Server.
But there are several ways to do this.
I'll mention trigger way.

• First you define a number column in your table.
• Then create a sequence.
• And create a "before trigger" using sequence on table.

1. You have a table like this:
   CREATE TABLE SERVICES
   (
   SERVICEID NUMBER(10) NOT NULL,
   SERVICENAME VARCHAR2(20 BYTE) NOT NULL
   )
2. Create a sequence:
   create sequence SERVICES_seq
   start with 1
   increment by 1
   nomaxvalue;
3. Create a before insert trigger:
   CREATE trigger tr_SERVICES
   before insert on SERVICES
   for each row
   begin
   select SERVICES_seq.nextval into :new.SERVICEID from dual;
   end;
   /

That's it!