Oracle Function with a select into problem

Question

Here is one that I cannot figure out. I'm trying to select the median of a set of events in a purchase qty. I have the selects working in SQL. It returns the correct answer for several sets of test data. However, when I put this into a function to be able to call during more complex queries it doesn't work. I've tested the function several different ways and it's looking like the select median into v_median2... is not working. Please help!
Here is the code... When this is run what ever is in v_plant is returned. IE: If you pass 1122 into with getmedian('4567','12345678-0001') this returns 4567 at the output. I've bypassed the v_plant and v_material in the select part below and it still output 4567.
If you run the select (with test data put in place of v_plant and v_material in a sqlplus window without the INTO v_median2) it would return a 12.
If you run this function as is it would return 4567.
Here is the output from the dbms_output tests.
4567
12345678-0001
4567
12345678-0001
4567
WHY?
CREATE OR REPLACE FUNCTION getmedian(v_plant IN VARCHAR2, v_material IN VARCHAR2)
RETURN NUMBER
AS
v_median2 NUMBER;
BEGIN
DBMS_OUTPUT.PUT_LINE(v_plant);
DBMS_OUTPUT.PUT_LINE(v_material);
SELECT MEDIAN INTO v_median2
FROM (SELECT ROWNUM as rownums,MEDIAN
FROM (SELECT abs(quantity_in_unit_entry) AS MEDIAN
FROM tbl_transactions
WHERE plant = v_plant
AND material = v_material
AND movement_type IN ('961','261','201')
ORDER BY quantity_in_unit_entry DESC))
WHERE ROWNUMs = ( select round(COUNT(1)/2,0) AS TOTAL2
from tbl_transactions t
WHERE plant = v_plant
AND material = v_material
AND t.movement_type IN ('961','261','201'));
DBMS_OUTPUT.PUT_LINE(v_plant);
DBMS_OUTPUT.PUT_LINE(v_material);
DBMS_OUTPUT.PUT_LINE(v_median2);
RETURN v_median2;
END;

Answer 1

It looks like another one of those cases where the pl/sql engine doesn't yet handle everything that the sql engine does. The usual solution is to execute the part that only works in sql dynamically. Try this:
CREATE OR REPLACE FUNCTION getmedian
  (v_plant    IN VARCHAR2,
   v_material IN VARCHAR2)
  RETURN         NUMBER
AS
  v_rownums      NUMBER          := 0;
  v_sql          VARCHAR2 (4000) := NULL;
  v_median2      NUMBER          := 0;
BEGIN
  SELECT ROUND (COUNT (1) / 2, 0)
  INTO   v_rownums
  FROM   tbl_transactions
  WHERE  plant = v_plant
  AND    material = v_material
  AND    movement_type IN
         ('961', '261', '201');
  v_sql :=
  'SELECT median
   FROM   (SELECT ROWNUM AS rownums,
                  median
           FROM   (SELECT   ABS (quantity_in_unit_entry)
                                AS median
                   FROM     tbl_transactions
                   WHERE    plant = :v_plant
                   AND      material = :v_material
                   AND      movement_type IN
                            (''961'', ''261'', ''201'')
                   ORDER BY quantity_in_unit_entry DESC))
   WHERE  rownums = :v_rownums';
  EXECUTE IMMEDIATE v_sql INTO v_median2
  USING v_plant, v_material, v_rownums;
  RETURN v_median2;
END getmedian;