Function error: Too many records

Question

I have writing a function that needs to return the total count of a sql statement. It will divide two calculated columns to get an average. I have two versions. Version 1 compiled successfully and I am trying to either run it in Reports or in the database and call it. I get an error stating that the function returns too many records. I understand that is a rule for stored functions but how can I modify the code to get it return one value for each time it is called?
Here is the main calculation. SUM(date1-date2) / (date1-date2) = Avg of Days
version1:
create or replace FUNCTION CALC_OVER_AGE
RETURN NUMBER IS
days_between NUMBER;
days_over NUMBER;
begin
select (determination_dt - Filed_dt), SUM(determination_dt - Filed_dt) into days_between, days_over
from w_all_cases_mv
where (determination_dt - Filed_dt) > 60
and ;
return (days_between/days_over);
END CALC_OVER_AGE;
version2:
CREATE OR REPLACE FUNCTION CALC_OVER_AGE (pCaseType VARCHAR2)
RETURN PLS_INTEGER IS
v_days_between W_ALL_CASES_MV.DAYS_BETWEEN%TYPE;
v_total NUMBER;
days_over NUMBER;
i PLS_INTEGER;
BEGIN
SELECT COUNT(*)
INTO i
FROM tab
WHERE case_type_cd = pCaseType
AND determination_dt - Filed_dt > 60;
IF i <> 0 THEN
select SUM(determination_dt-Filed_dt), days_between
into v_total, v_days_between
from tab
where determination_dt - Filed_dt > 60;
RETURN v_total/v_days_between;
ELSE
RETURN 0;
END IF;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END CALC_OVER_AGE;

Answer 1

Table Structure:
WB_CASE_NR NUMBER(10)
RESPONDENT_TYPE_CD VARCHAR2(10)
INV_LOCAL_CASE_NR VARCHAR2(14)
CASE_TYPE_CD VARCHAR2(10)
FILED_DT DATE
FINAL_DTRMNTN_DT DATE
REPORTING_NR VARCHAR2(7)
INVESTIGATOR_NAME VARCHAR2(22)
OSHA_CD VARCHAR2(5)
FEDERAL_STATE VARCHAR2(1)
RESPONDENT_NM VARCHAR2(100)
DAYS_BETWEEN NUMBER
LAST_NM VARCHAR2(20)
FIRST_NM VARCHAR2(20)
DETERMINATION_DT DATE
DETERMINATION_TYPE_CD VARCHAR2(2)
FINAL_IND_CD VARCHAR2(1)
DESCRIPTION VARCHAR2(400)
DETERMINATION_ID NUMBER(10)
ALLEGATION_CD VARCHAR2(1)
ALGDESCRIPTION VARCHAR2(50)
Output is for Reports, I am trying to get the last calculation, which is the Average Days. The reports is grouped on Case Types and has several bucket counts for each like this.
Case Type Count All Completed Pending Over Age Avg Days
A 5 3 4 2 15
Z 10 7 6 3 30
4 8 3 5 4 22
To get the Avg Days, the Over Age calculation is used as well as the Days Between (Determination_Dt - Filed_Dt). That is the (date1-date2) example that I gave in my first post. So the calcuation would be the SUM(Days_Between) / Days_Between.