以Mysql 4.1版本为分界线，两种加密方式
Mysql323加密：（16位）
select old_password(‘root‘); //Mysql自带加密函数old_password(str)
mysql> select old_password(‘root‘); +----------------------+ | old_password(‘root‘) | +----------------------+ | 67457e226a1a15bd | +----------------------+ 1 row in set (0.00 sec)
MysqlSHA1加密：（去掉*号40位，单向加密，只能通过密码库匹配出来）
select password(‘root‘); //Mysql自带加密函数password(str)
mysql> select password(‘root‘); +-------------------------------------------+ | password(‘root‘) | +-------------------------------------------+ | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B | +-------------------------------------------+ 1 row in set (0.00 sec)
原文：http://www.cnblogs.com/captainRoB/p/7164075.html