mysql生成随机数

DROP FUNCTION IF EXISTS rand_string; delimiter // CREATE FUNCTION rand_string(l_num tinyint UNSIGNED,l_type tinyint UNSIGNED) RETURNS varchar(127) BEGIN -- Function : rand_string -- Author : dbachina#dbachina.com -- Date : 2010/5/30 -- l_num : The length of random string -- l_type: The string type -- 1.0-9 -- 2.a-z -- 3.A-Z -- 4.a-zA-Z -- 5.0-9a-zA-Z --  : -- mysql> select rand_string(12,5) random_string; -- +---------------+ -- | random_string | -- +---------------+ -- | 3KzGJCUJUplw | -- +---------------+ -- 1 row in set (0.00 sec) DECLARE i int UNSIGNED DEFAULT 0; DECLARE v_chars varchar(64) DEFAULT '0123456789'; DECLARE result varchar ( 255) DEFAULT ''; IF l_type = 1 THEN SET v_chars = '0123456789'; ELSEIF l_type = 2 THEN SET v_chars = 'abcdefghijklmnopqrstuvwxyz'; ELSEIF l_type = 3 THEN SET v_chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; ELSEIF l_type = 4 THEN SET v_chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; ELSEIF l_type = 5 THEN SET v_chars = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; ELSE SET v_chars = '0123456789'; END IF; WHILE i < l_num DO SET result = concat( result,substr(v_chars,ceil(rand()*(length(v_chars)-1)),1) ); SET i = i + 1; END WHILE; RETURN result; END; // delimiter ; 

转自http://www.dbachina.com/2010/05/31/mysql_random_string_function/