該函數能夠檢查身份證號碼是否正確

			
CREATE DEFINER=`neo`@`%` FUNCTION `check_id_number`(`idnumber` CHAR(18))
	RETURNS enum('true','false')
	LANGUAGE SQL
	NOT DETERMINISTIC
	NO SQL
	SQL SECURITY DEFINER
	COMMENT ''
BEGIN
DECLARE status ENUM('true','false') default 'false';
DECLARE verify CHAR(1);
DECLARE sigma INT;
DECLARE remainder INT;

IF length(idnumber) = 18 THEN
	set sigma = cast(substring(idnumber,1,1) as UNSIGNED) * 7
		+cast(substring(idnumber,2,1) as UNSIGNED) * 9
		+cast(substring(idnumber,3,1) as UNSIGNED) * 10
		+cast(substring(idnumber,4,1) as UNSIGNED) * 5
		+cast(substring(idnumber,5,1) as UNSIGNED) * 8
		+cast(substring(idnumber,6,1) as UNSIGNED) * 4
		+cast(substring(idnumber,7,1) as UNSIGNED) * 2
		+cast(substring(idnumber,8,1) as UNSIGNED) * 1
		+cast(substring(idnumber,9,1) as UNSIGNED) * 6
		+cast(substring(idnumber,10,1) as UNSIGNED) * 3
		+cast(substring(idnumber,11,1) as UNSIGNED) * 7
		+cast(substring(idnumber,12,1) as UNSIGNED) * 9
		+cast(substring(idnumber,13,1) as UNSIGNED) * 10
		+cast(substring(idnumber,14,1) as UNSIGNED) * 5
		+cast(substring(idnumber,15,1) as UNSIGNED) * 8
		+cast(substring(idnumber,16,1) as UNSIGNED) * 4
		+cast(substring(idnumber,17,1) as UNSIGNED) * 2;
	set remainder = MOD(sigma,11);
	set verify = (case remainder
		when 0 then '1' when 1 then '0' when 2 then 'X' when 3 then '9'
		when 4 then '8' when 5 then '7' when 6 then '6' when 7 then '5'
		when 8 then '4' when 9 then '3' when 10 then '2' else '/' end
	);

END IF;

IF right(idnumber,1) = verify THEN
	set status = 'true';
END IF;

RETURN status;

END
			
			

首先我們使用正確身份證號碼進行測試，返回true

			
mysql> select check_id_number('330702198003090915');
+---------------------------------------+
| check_id_number('330702198003090915') |
+---------------------------------------+
| true                                  |
+---------------------------------------+
1 row in set (0.01 sec)
			
			

長度不符合18位直接返回false.

			
mysql> select check_id_number('33070219800309');
+-----------------------------------+
| check_id_number('33070219800309') |
+-----------------------------------+
| false                             |
+-----------------------------------+
1 row in set (0.00 sec)	

mysql> select check_id_number('33070219800309091457889');
+--------------------------------------------+
| check_id_number('33070219800309091457889') |
+--------------------------------------------+
| false                                      |
+--------------------------------------------+
1 row in set, 1 warning (0.00 sec)
			
			

隨便改譯為數，校驗失敗返回 false

			
mysql> select check_id_number('330702198003090914');
+---------------------------------------+
| check_id_number('330702198003090914') |
+---------------------------------------+
| false                                 |
+---------------------------------------+
1 row in set (0.00 sec)