今天下載了MySQL 8.0 ，但是用Navicat連線時報錯1251，
原來新版的MySQl8.0和Mysql5.0的加密方式不一樣，
需要更改配置（即更改加密方式）。

1.在命令列登入mysql:

mysql -u root -p

C:\Program Files\MySQL\MySQL Server 8.0\bin>mysql -u root -p
Enter password: ******

2.檢視使用者許可權資訊：
select host,user,plugin,authentication_string from mysql.user;

mysql> select host,user,plugin,authentication_string from mysql.user;
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
 

| host      | user             | plugin                | authentication_string                                                  |
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
| localhost | mysql.infoschema | caching_sha2_
 
password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.session    | caching_sha2_password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | mysql.sys        | caching_sha2_password | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED |
| localhost | root             | caching_sha2_
 
password | $A$005$|{jxw<[P4yC9.IXQMPtTL5BLkbHodLmBNdtnRPJsFbVwY2yAswsprqKA |
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
4 rows in set (0.57 )

提示：host表示許可權（localhost是本地，%不限制）；plugin為‘cahing_sha2_password’則需改密碼。

3.更改加密方式：
ALTER USER ‘root’@’%’ IDENTIFIED WITH mysql_native_password BY ‘newpassword’;
‘newpassword’是新的密碼；

mysql> ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY 'newpassword';
ERROR 1396 (HY000): Operation ALTER USER failed for 'root'@'%'

這裡出錯，把‘%’改為‘localhost’
ALTER USER ‘root’@’localhost’ IDENTIFIED WITH mysql_native_password BY ‘newpassword’;

mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'yechunrong';
Query OK, 0 rows affected (0.78 sec)

修改成功。

4.在Navicat輸入新的密碼就可以成功連線！