Сделайте это в SQL Plus:
set serverout on
declare
l_val varchar2(30) := 'hello world';
procedure myproc (p_val in out varchar2) is
begin
dbms_output.put_line('p_val was ' || p_val);
p_val := 'something else';
end;
begin
myproc(l_val);
dbms_output.put_line('l_val is now ' || l_val);
end;
/
Вы должны увидеть результат:
p_val was hello world
l_val is now something else