Best way of optimizing..

Question

Hi All,
I have a procedure as follows, but i am not sure whether it is a best way of doing it or not.
Can any one of you please advise me the best way of doing it.
CREATE OR REPLACE procedure xx_test_credit1 (p_credit in number)
is
l_even_first_digit Number;
l_even_second_digit Number;
l_even_third_digit Number;
l_even_fourth_digit Number;
l_even_fifth_digit Number;
l_odd_first_digit Number;
l_odd_second_digit Number;
l_odd_third_digit Number;
l_odd_fourth_digit Number;
l_odd_fifth_digit Number;
l_odd_sixth_digit Number;
l_len_value Number;
l_sum_value Number;
begin
select substr(p_credit,'10',1) into l_even_first_digit from dual;
select substr(p_credit,'8',1) into l_even_second_digit from dual;
select substr(p_credit,'6',1) into l_even_third_digit from dual;
select substr(p_credit,'4',1) into l_even_fourth_digit from dual;
select substr(p_credit,'2',1) into l_even_fifth_digit from dual;
select substr(p_credit,'11',1) into l_odd_first_digit from dual;
select substr(p_credit,'9',1) into l_odd_second_digit from dual;
select substr(p_credit,'7',1) into l_odd_third_digit from dual;
select substr(p_credit,'5',1) into l_odd_fourth_digit from dual;
select substr(p_credit,'3',1) into l_odd_fifth_digit from dual;
select substr(p_credit,'1',1) into l_odd_sixth_digit from dual;
l_even_first_digit:=l_even_first_digit*2;
l_even_second_digit:=l_even_second_digit*2;
l_even_third_digit:=l_even_third_digit*2;
l_even_fourth_digit:=l_even_fourth_digit*2;
l_even_fifth_digit:=l_even_fifth_digit*2;
l_sum_value:=(l_even_first_digit+l_even_second_digit+l_even_third_digit+l_even_fourth_digit+l_even_fifth_digit+
l_odd_first_digit+l_odd_second_digit+l_odd_third_digit+l_odd_fourth_digit+l_odd_fifth_digit+l_odd_sixth_digit);
if mod(l_sum_value,10)=0 then
dbms_output.put_line('The number is valid credit card number');
else
dbms_output.put_line('The number is not valid credit card number');
end if;
select length(p_credit) into l_len_value from dual;
if l_len_value<>11
then
dbms_output.put_line('Please enter 11 digit value');
end if;
end xx_test_credit1;
Thanks a lot.
Zaheer.

Answer 1

How about:
CREATE OR REPLACE PROCEDURE xx_test_credit1 (p_credit IN VARCHAR2) IS
        l_len_value  PLS_INTEGER  := NVL(LENGTH(p_credit), 0);
        l_sum_value  PLS_INTEGER := 0;
BEGIN
        IF l_len_value != 11 THEN
                dbms_output.put_line ('Please enter 11 digit value');
        ELSE
                FOR i IN 1 .. l_len_value
                LOOP
                        l_sum_value := l_sum_value + (TO_NUMBER(SUBSTR(p_credit, i, 1)) * (MOD(i, 2)+1));
                END LOOP;
                IF MOD (l_sum_value, 10) = 0 THEN
                        dbms_output.put_line('The number is valid credit card number');
                ELSE
                        dbms_output.put_line('The number is not valid credit card number');
                END IF;
        END IF;
END;
/If you are already in PL/SQL it will be more effient than calling a SELECT statement to do the calculation.
As others have mentioned you don't need to do:
select substr(p_credit,'10',1) into l_even_first_digit from dual;Just do:
l_even_first_digit := substr(p_credit,'10',1);and the same for:
select length(p_credit) into l_len_value from dual;Just do:
l_len_value := length(p_credit);Also your parameter you pass in "p_credit in number", should not be a "number"
if the card number starts with a leading 0 then the
if l_len_value != 11test will not work
(If you pass in 00000000001 you only realy pass in 1 - which is not 11 digits long)
You probably need to pass in a VARCHAR2 instead, to preseve the leading 0's.
Also
substr(p_credit,'10',1)
The second parameter to SUBSTR is a NUMBER, not a string.
GP>