Navicat连接新版MySQL 8.0，解决错误1251.

今天下载了MySQL 8.0 ，但是用Navicat连接时报错1251，
原来新版的MySQl8.0和Mysql5.0的加密方式不一样，
需要更改配置（即更改加密方式）。

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1.在命令行登录mysql:

mysql -u root -p

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

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2.查看用户权限信息：
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$005$|{j
xw<[P4yC9.IXQMPtTL5BLkbHodLmBNdtnRPJsFbVwY2yAswsprqKA |
+-----------+------------------+-----------------------+------------------------------------------------------------------------+
4 rows in set (0.57 )

提示：host表示权限（localhost是本地，%不限制）；plugin为‘cahing_sha2_password’则需改密码。

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

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

这里出错，把‘%’改为‘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。

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4.在Navicat输入新的密码就可以成功连接！