Turn a procedure into a Function?

Question

I've got a procedure that generates a random 4 digit pin as per my unique requirements. I'd like to turn it into a function so that I could call it in an updated statement to update rows in a table with a random pin number.
Would it be possible to turn this into a function? Never written one before and could use a steer please.
CREATE OR REPLACE PROCEDURE TEST.scr_pin_generator
IS
v_candidate_pin NUMBER (4);
v_pin_1 NUMBER (1);
v_pin_2 NUMBER (1);
v_pin_3 NUMBER (1);
v_pin_4 NUMBER (1);
v_pin_count NUMBER := 0;
v_done CHAR(1) := 'N';
c_no_of_pins_reqd NUMBER := 200000;
BEGIN
WHILE v_done = 'N'
LOOP
v_candidate_pin := ROUND (DBMS_RANDOM.VALUE (1, 9999));
IF v_candidate_pin < 1000
THEN
-- dbms_output.put_line('Reject1='||to_char(v_candidate_pin));
GOTO end_loop;
END IF;
v_pin_1 := SUBSTR (v_candidate_pin, 1, 1);
v_pin_2 := SUBSTR (v_candidate_pin, 2, 1);
v_pin_3 := SUBSTR (v_candidate_pin, 3, 1);
v_pin_4 := SUBSTR (v_candidate_pin, 4, 1);
/* avoid all numbers the same */
IF v_pin_1 = v_pin_2
THEN
-- dbms_output.put_line('Reject2='||to_char(v_candidate_pin));
GOTO end_loop;
END IF;
/* avoid consecutive up */
IF v_pin_2 = v_pin_1 + 1 AND v_pin_3 = v_pin_2 + 1
THEN
-- dbms_output.put_line('Reject3='||to_char(v_candidate_pin));
GOTO end_loop;
END IF;
/* avoid consecutive down */
IF v_pin_2 = v_pin_1 - 1 AND v_pin_3 = v_pin_2 - 1
THEN
-- dbms_output.put_line('Reject4='||to_char(v_candidate_pin));
GOTO end_loop;
END IF;
v_pin_count := v_pin_count + 1;
INSERT INTO random_test
VALUES (v_candidate_pin);
--dbms_output.put_line('Number='||to_char(v_candidate_pin));
<<end_loop>>
IF v_pin_count = c_no_of_pins_reqd
THEN
v_done := 'Y';
END IF;
END LOOP;
COMMIT;
END;
/

Answer 1

I think something like this will give you what you want.
SQL> create table t as select object_name from dba_objects where rownum < 101;
Table created.
SQL> alter table t add pin number(4);
Table altered.
SQL> update t set pin = floor(dbms_random.value(1000, 9999));
100 rows updated.
SQL> select * from t;
OBJECT_NAME                          PIN
ICOL$                                4432
I_USER1                              2994
CON$                                 7600
UNDO$                                1970
C_COBJ#                              3502
I_OBJ#                               1052
PROXY_ROLE_DATA$                     7310
I_IND1                               1318
I_CDEF2                              8377
I_PROXY_ROLE_DATA$_1                 6997
FILE$                                4116
UET$                                 7381
I_FILE#_BLOCK#                       8885
I_FILE1                              6456
.