title: SQL - cannot compile body of <package> without its specification
body: <p>Trying to create a package that will do a calculation: A procedure holds a variable with a number, I will then call the package along with the variable, and a calculation will be made and printed out. However I get that the "my_pkg is invalid" and "cannot compile body of  without its specification"
  Any input is much welcome</p>
  
  <pre><code>create or replace package my_pkg as
  Procedure do_calc(v_add number);
  v_sum number;
  v_number number;
  end my_pkg;
  /
  
  create or replace package body my_pkg as
  Procedure do_calc (v_add number) is
  v_sum number;
  v_number number;
  begin
  v_number := 10; 
  v_sum := v_number + v_add;
  dbms_output.put_line('sum is: '||v_sum);
  end do_calc;
  end my_pkg;
  /
  </code></pre>