Getting A PLS-00103 error when trying to execute PLSQL print sequence code-CodePudding

DECLARE
n number := 12;
sum number;
BEGIN
    dbms_output.put_line(n);
    WHILE n>0 LOOP
      sum := 0;
      FOR i IN 0..n-1 LOOP
        IF n%i = 0 THEN
          sum := sum   i;
        END IF;
      END LOOP;
      dbms_output.put_line(sum);
      n := sum;
    END LOOP;
END;

I get errors such as these

Can someone explain why , I am trying to print an Alequot Sequence

CodePudding user response：

Two mistakes, both easily fixable.

First, sum is a PL/SQL keyword - you shouldn't use it as a variable name. You can change it to something like sum_ (with a trailing underscore), or l_sum ("l" to suggest "local variable"), etc.

Second, n%i is the modulo notation in other languages; PL/SQL uses mod(n, i).

Make these two changes and your code will work.

If you care to, you can make the code more efficient by looping from 1 to n/2 - but that's just math, it has nothing to do with "coding".

You are also doing a few other odd things. If you start with n > 0 (which you must - the Aliquot sequence only makes sense for positive integers), the updated value of n (after the inner loop) will always be greater than 0.

Worse: while some Aliquot sequences end in 1, not all do. Some end in a perfect number (for example if the input itself is a perfect number). Some sequences become periodic, with a period of 2 or more. It is also not known whether all Aliquot sequences are eventually periodic (ending in 1, in a perfect number, or a cyclical sequence of period 2 or more). So, to avoid trouble, you should put a limit to how far the computation may continue. (This is also "just math" but it does have a direct bearing on the coding too.)