Navicat连接不上，总是报错1251；
原因是MySQL8.0版本的加密方式和MySQL5.0的不一样，连接会报错。
更改加密方式
1.先通过命令行进入mysql的root账户：
PS C:\Windows\system32> mysql -uroot -p再输入root的密码：
Enter password: ******
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18
Server version: 8.0.11 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>2.更改加密方式：
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'password' PASSWORD EXPIRE NEVER;
Query OK, 0 rows affected (0.10 sec)3.更改密码：
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';
Query OK, 0 rows affected (0.35 sec)4.刷新：
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.28 sec)// 如果报错 ERROR 1396 (HY000): Operation ALTER USER failed for ‘root’@’%’ ：
则是远程访问权限不正确，先选择数据库，查看一下再更改：
mysql> use mysql;
Database changed
mysql> select user,host from user;
+------------------+-----------+
| user | host |
+------------------+-----------+
| mysql.infoschema | localhost |
| mysql.session | localhost |
| mysql.sys | localhost |
| root | localhost |
+------------------+-----------+
5 rows in set (0.00 sec)
