shell> mysql
                      Client does not support authentication protocol requested
                      by server; consider upgrading MySQL client
                    
                    
                      官方的说法是
                    
                    
                      MySQL 4.1 and up uses an authentication protocol based on a password hashing algorithm that is incompatible with that used by older clients. .....
                    
                    
                      
                       
                    
                    
                      如果你升级mysql到4.1以上版本后遇到以上问题,请先确定你的mysql client 是4.1或者更高版本.(WINDOWS下有问题你就直接跳到下面看解决方法了,因为MYSQL 在WINDOWS是client和server一起装上了的)
                    
                    
                      请使用以下两种方法之一
                    
                    
                      其一:
                    
                    mysql> SET PASSWORD FOR -> 'some_user'@'some_host' = OLD_PASSWORD('newpwd'); 
                    
                      其二:
                    
                    mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('newpwd') -> WHERE Host = 'some_host' AND User = 'some_user'; mysql> FLUSH PRIVILEGES; 
                    上面红色的部分请按自己实际情况修改....
                    这样做后,连接就会正常了@!