Why are none of my conditions being met in this proc? - oracle

Question

So i have a stored procedure (that's been watered down below for demo purposes) that aren't passing any conditions and thus aren't inserting/passing any values into my table. I've tried converting the varchar/string that is being passed in by Java to a number but nothing is working. Below is my 'simplified code'
Create or Replace Procedure SAMPLE(rValue IN VARCHAR)
IS
v_Max value.value%type;
v_forecast value.value%type;
BEGIN
--
SELECT BUFFER_MAX_VALUE
INTO v_MAX
FROM look_up;
--
EXCEPTION
WHEN no_data_found
THEN SELECT 0
INTO v_forecast
FROM DUAL;
--
IF to_Number(rValue) < 0 OR to_Number(rValue) > v_MAX)
THEN
dbms_output.put_line('IF1 Works');
insert into value(value_id, value)
values(1, rValue);
ELSIF rValue is null OR to_Number(rValue) = 0
THEN
dbms_output.put_line('IF1A ONLY Works');
END IF;
ELSE
insert into value(value_id, value)
values(1, v_forecast);
dbms_output.put_line('IF1 ELSE ONLY Works');
END SAMPLE;
i tried passing the following in:
BEGIN
SAMPLE('-7');
END;

Answer 1

If the first SELECT BUFFER_MAX_VALUE returns anything, nothing else will be executed because you put absolutely everything into the EXCEPTION section. If you meant to handle that statement only, you should have enclosed it into its own BEGIN-END block, such as
create procedure ...
begin
-- its own begin starts now
begin
select buffer_max_value into v_max
from look_up;
exception
when no_data_found then
-- do something here
end;
-- its own end ends now
-- put the rest of your code here
end;
By the way, does LOOK_UP table contain no rows or only one row, always? Because, as SELECT you wrote contains no WHERE clause, it might raise TOO_MANY_ROWS (which you should also handle).
You declared rValue as VARCHAR2, and then apply TO_NUMBER to it. Why don't you declare it to be a NUMBER, instead? Because, nothing prevents you from passing, for example, 'XYZ' to the procedure, and then TO_NUMBER will miserably fail with the INVALID NUMBER error.
[EDIT: some more exception handling]
EXCEPTION section handles all exceptions that happen in that BEGIN-END block, no matter how many SELECT statements you have. Though, you won't know which one failed, unless you include a little bit of additional (simple) programming.
Note that this is just for showing what I meant; don't handle errors with DBMS_OUTPUT (as, most probably, nobody will see it), and rarely you'd want to handle errors with WHEN OTHERS.
create procedure ...
l_position number;
begin
l_position := 1;
select ... into ... from ...;
l_position := 2;
select ... into ...
exception
when others then
dbms_output.put_line('Error on position ' || l_position ||' '|| sqlerrm);
raise;
end;

Answer 2

As far as I can tell, you wanted the exception section to trap the situation where there is nothing in the lookup table. In that case, you set v_forecast and then continue. That means you need to put the select inside its own block.
I also avoiding multiple to_number calls by setting a constant.
I got rid of the unnecessary select from dual.
I also really really hope that you do not have a table named VALUE with a column named VALUE. Choose more meaningful names.
See how this works for you.
CREATE OR REPLACE PROCEDURE sample (rvalue IN VARCHAR2)
IS
c_rvalue CONSTANT NUMBER := rvalue;
v_max VALUE.VALUE%TYPE;
v_forecast VALUE.VALUE%TYPE;
BEGIN
BEGIN
SELECT buffer_max_value INTO v_max FROM look_up;
EXCEPTION
WHEN NO_DATA_FOUND
THEN
v_forecast := 0;
END;
IF c_rvalue < 0 OR c_rvalue > v_max
THEN
DBMS_OUTPUT.put_line ('IF1 Works');
INSERT INTO VALUE (value_id, VALUE)
VALUES (1, rvalue);
ELSIF c_rvalue IS NULL OR c_rvalue = 0
THEN
DBMS_OUTPUT.put_line ('IF1A ONLY Works');
ELSE
INSERT INTO VALUE (value_id, VALUE)
VALUES (1, v_forecast);
DBMS_OUTPUT.put_line ('IF1 ELSE ONLY Works');
END IF;
END sample;