oracle - Are PL/SQL variables in cursors effectively the same as bind parameters?

Question

I've heard that using bind variables is (can be) more efficient, because for subsequent calls with a different bind value, the query itself is still the same, so it doesn't need to be parsed anymore.

I understand why this is the case for fixed values. In the cursor below, the value is fixed on 1. If I have a different cursor that is the same, except the 1 becomes 2, it is a diffent query. Clear so far.

declare
  cursor C_CURSOR is 
    select * from TESTTABLE pt where pt.ID = 1;

But I wondered if this is also the case when using PL/SQL variables inside the cursor. Are they expanded as if it's a fixed value, or are they interpreted as bind variables.

I've searched far and wide, but everywhere I find examples about literals, as in the case above, but no clear explanation about the use of PL/SQL variables.

In other words, of the two snippets below, is the second one potentially more efficient, or are they essentially the same?

With a PL/SQL variable directly in the cursor:

declare
  V_TEST integer := 1;

  cursor C_CURSOR is 
    select * 
    from 
      TESTTABLE pt
    where
      pt.ID = V_TEST;

begin
  for r in C_CURSOR loop
    null;
  end loop;
end;

With a bind variable:

declare
  V_TEST int := 1;

  cursor C_CURSOR(B_TEST int) is 
    select * 
    from 
      TESTTABLE pt
    where
      pt.ID = B_TEST;

begin
  for r in C_CURSOR(V_TEST) loop
    null;
  end loop;
end;

Answer 1

First of all, good question.

I would like to make a small quote:

Every reference to a PL/SQL variable is in fact a bind variable.

Having said that,

PL/SQL itself takes care of most of the issues to do with bind variables, to the point where most code that you write already uses bind variables without you knowing. Take, for example, the following bit of PL/SQL:

create or replace procedure dsal(p_empno in number)
as
  begin
    update emp
    set sal=sal*2
    where empno = p_empno;
    commit;
  end;
/

Now you might be thinking that you've got to replace the p_empno with a bind variable. However, the good news is that every reference to a PL/SQL variable is in fact a bind variable.

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