"Boolean" parameter for Oracle stored procedure

You can use Booleans as parameters to stored procedures:

procedure p (p_bool in boolean) is...

However you cannot use Booleans in SQL, e.g. select statements:

select my_function(TRUE) from dual; -- NOT allowed

For a number parameter there is no way to declaratively add a "check constraint" to it, you would have to code some validation e.g.

procedure p (p_num in number) isbegin   if p_num not in (0,1) then      raise_application_error(-20001,'p_num out of range');   end if;   ...

Yes and no.You can do..

create or replace package t_bool is  subtype t_bool_num IS PLS_INTEGER RANGE 0..1;  function f_test (i_bool_num t_bool_num) return varchar2;end t_bool;/create or replace package body t_bool is  function f_test (i_bool_num t_bool_num) return varchar2 is  begin    if i_bool_num = 0 then       return 'false';    elsif i_bool_num = 1 then      return 'true';    elsif i_bool_num is null then      return 'null';    else      return to_char(i_bool_num);    end if;  end;end t_bool;/

The good news is that, if you do

exec dbms_output.put_line(t_bool.f_test(5));

it reports an error.

The bad news is that if you do

select t_bool.f_test(5) from dual;

then you don't get an error