Create Primary Key in Sql table

How To create primary key in sql table :

You have a code(for table)like this:

create table person( name     varchar2(5),
                               Id_no       number(3),
                              Address    number(10));

Now you want to make Id_no as Primary key: so there are two methods to make a column primary key one in table order and other one is column order.
===================================================
Column  Order:
create table person( name    varchar2(5),
                               Id_no     number(3) primary key,
                              Address  number(10));
==================================================
Table Order:
create table person( name varchar2(5),
                               Id_no number(3),
                              Address number(10),
                             primary key(Id_no));