18-digit ID card Verification Algorithm

ID card verification code algorithm
ID card verification code generation method:
SIGMA (AI x WI) (mod 11)

I: the serial number of the character from the start to the left, including the verification code;

AI indicates the number character value at position I;

The weighted factor at the I position of wi. Its value is Wi = Mod (Power (2, (n-1), 11)

I 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Wi 7 9 10 5 8 4 2 1 6 3 7 9 10 5 8 4 2 1

Check Code:
SIGMA (AI x WI) (mod 11) 0 1 2 3 4 5 6 7 8 9 10
Verification Code character value: AI 1 0x9 8 7 6 5 4 3 2

1. Create or replace function id_15to18 (idcardnum varchar2) return varchar2 is
2. Result varchar2 (20 );
3. I smallint;
4. Num smallint: = 0;
5. Snum varchar2 (2 );
6. Code char (1 );
7. Temp17 varchar2 (20 );
8. Begin
10. If length (idcardnum) = 18 or idcardnum is null then
11. Result: = upper (idcardnum );
12. Elsif length (idcardnum) = 15 then
13. Temp17: = substr (idcardnum, 1, 6) | '19' | substr (idcardnum, 7, 9 );
14. I: = 18;
16. While I> 1 Loop
17. Num: = num + Mod (Power (2, I-1), 11) * substr (temp17, 19-I, 1 );
18. I: = I-1;
19. End loop;
21. Num: = Mod (Num, 11 );
23. Snum: = num | '';
24. If num = 0 then
25. Code: = '1 ';
26. Elsif num = 1 then
27. Code: = '0 ';
28. Elsif num = 2 then
29. Code: = 'X ';
30. Else
31. Code: = (12-num) | '';
32. End if;
33. Result: = temp17 | code;
34. Else
35. Result: = idcardnum;
36. End if;
37. Return result;
38. Exception
39. When others then
40. Dbms_output.put_line ('erroe '| idcardnum );
42. End id_15to18;