mysql 4.1以后, 采用了一种新的用户认证协议, 对于老的客户端会出现不支持认证协议的错误, 以下是官方网站的解决方法﹔
１upgrade all client programs to use a 4.1.1 or newer client library.
更新客户端库，这需要更新ｐｈｐ的扩展库，对于老的ａｐｉ ｐｈｐ已经不提供了这样的扩展库了
２when connecting to the server with a pre-4.1 client program, use an account that still has a pre-4.1-style password.
使用以前建立的账号连接，对于在新的认证协议下建立的账户就不行了
３reset the password to pre-4.1 style for each user that needs to use a pre-4.1 client program. this can be done using the set password statement and the old_password() function: mysql> set password for
alternatively, use update and flush privileges: mysql> update mysql.user set password = old_password('newpwd') -> where host = 'some_host' and user = 'some_user';
mysql> flush privileges;
substitute the password you want to use for ``newpwd'' in the preceding examples. mysql cannot tell you what the original password was, so you'll need to pick a new one.
这是一个不错的办法，新建立的账号采用老式的加密协议
４tell the server to use the older password hashing algorithm:
start mysqld with the --old-passwords option.
这样新认证协议的优点就没法使用了
５assign an old-format password to each account that has had its password updated to the longer 4.1 format. you can identify these accounts with the following query: mysql> select host, user, password from mysql.user
-> where length(password) > 16;
for each account record displayed by the query, use the host and user values and assign a password using the old_password() function and either set password or update, as described earlier.
