(PL\SQL) Luhn 检查号码生成

Question

如果我对数列运行 Luhn 公式检查，并且返回数字为 0，则数列是有效的（不是随机的）。我有一个随机数序列，但我需要一个 Luhn 数生成器，它返回一个数字。这个数字应该填写随机数序列以用 0 重新调整 Luhn 公式检查。

如何将这个 Luhn 数生成器创建为函数？

Answer 1

此结果适用于所有长度的数列。

CREATE OR REPLACE luhn_num (orig_num IN NUMBER)
RETURN STRING IS
  num_len NUMBER(20) := length(orig_num);
  result_num NUMBER(10);
  i NUMBER(10);
  temp_num NUMBER(10);
  sum_num NUMBER(10) := 0;

BEGIN
  IF MOD(num_len,2) = 0 THEN 
    FOR i IN 1..num_len LOOP
      IF MOD(i,2) = 0 THEN
        IF length(to_number(substr(orig_num,i,1))*2) > 1 THEN
          sum_num :=  sum_num + to_number(substr(to_number(substr(orig_num,i,1))*2,1,1)) + to_number(substr(to_number(substr(orig_num,i,1))*2,2,1));
        ELSE
          sum_num := sum_num + (to_number(substr(orig_num,i,1))*2);
        END IF;
      ELSE
        sum_num := sum_num + to_number(substr(orig_num,i,1));
      END IF;
    END LOOP;
  ELSE
    FOR i IN 1..num_len LOOP
      IF MOD(i,2) <> 0 THEN
        IF length(to_number(substr(orig_num,i,1))*2) > 1 THEN
          sum_num :=  sum_num + to_number(substr(to_number(substr(orig_num,i,1))*2,1,1)) + to_number(substr(to_number(substr(orig_num,i,1))*2,2,1));
        ELSE
          sum_num := sum_num + (to_number(substr(orig_num,i,1))*2);
        END IF;
      ELSE
        sum_num := sum_num + to_number(substr(orig_num,i,1));
      END IF;
    END LOOP;
  END IF;

  temp_num := 10 - to_number(substr(sum_num,length(sum_num),1));

  IF temp_num = 10 THEN
    result_num := 0;
  ELSE
    result_num := temp_num;
  END IF;

  RETURN result_num ;
END;