IN parameter to Oracle Function - oracle

Question

I have an Oracle function which accepts few IN parameters of number and varchar2 datatype and also it return a number datatype. Within the function, I'm selecting from a table with the IN parameters are applied in the 'WHERE' clause. By doing this, this filters is not applied to the select query instead it is skipping that condition. I need to explicitly declare a variables to store the values from IN parameter and then I need to use these variables in the WHERE clause. Not sure why this is required. Could you please help to resolve this without using the additional variables.
Below is the function, which I am using.
create or replace FUNCTION AGG_NC8B_FN (
FACTORY_ID NUMBER,
REPORTING_PERIOD NUMBER,
GRANULARITY_TYPE_TXT VARCHAR2,
GRANULAROTY_LEVEL_TXT VARCHAR2,
CONDITION_ID NUMBER)
RETURN NUMBER
IS
CAL_VALUE OCT_DMA_MOMIS.FCT_KSTACK_AGGREGATION.AGGREGATE_VALUE_DEC%TYPE;
-- temporary variables --not sure why this is required?
A number;
B number;
C varchar2(100);
D varchar2(100);
E number;
BEGIN
A:=FACTORY_ID;
B:=REPORTING_PERIOD;
C:=GRANULARITY_TYPE_TXT;
D:=GRANULAROTY_LEVEL_TXT;
E:=CONDITION_ID;
SELECT DECODE(B.AGGREGATE_VALUE_DEC,0,0,((A.AGGREGATE_VALUE_DEC/B.AGGREGATE_VALUE_DEC)*100))
INTO CAL_VALUE
FROM (SELECT AGGREGATE_VALUE_DEC
FROM OCT_DMA_MOMIS.FCT_KSTACK_AGGREGATION
WHERE FK_FIGURE_ID =30121
AND FK_FACTORY_ID =A
AND LK_REPORTING_PERIOD =B
AND GRANULARITY_TYPE_TXT=C
AND GRANULAROTY_LEVEL_TXT=D
AND FK_CONDITION_ID =E) A ,
(SELECT AGGREGATE_VALUE_DEC
FROM OCT_DMA_MOMIS.FCT_KSTACK_AGGREGATION
WHERE FK_FIGURE_ID =30122
AND FK_FACTORY_ID =A
AND LK_REPORTING_PERIOD =B
AND GRANULARITY_TYPE_TXT=C
AND GRANULAROTY_LEVEL_TXT=D
AND FK_CONDITION_ID =E
) B ;
RETURN CAL_VALUE;
END AGG_NC8B_FN;

Answer 1

Your function parameters and columns have same names (GRANULARITY_TYPE_TXT for example). Use different names or qualify function parameters with the name of the function:
-- wrong:
declare
function f(object_name in varchar2) return number is
l_id number;
begin
select object_id
into l_id
from all_objects
where object_name = object_name -- equals to (object name is not null)
and object_type = 'VIEW';
return l_id;
end;
begin
dbms_output.put_line(f('USER_OBJECTS'));
end;
> ORA-01422: exact fetch returns more than requested number of rows
-- right way:
declare
function f(object_name in varchar2) return number is
l_id number;
begin
select object_id
into l_id
from all_objects
where object_name = f.object_name -- subprogram_name.parameter_name
and object_type = 'VIEW';
return l_id;
end;
begin
dbms_output.put_line(f('USER_OBJECTS'));
end;
> 12345