报错原因：ERROR 1045 (28000): Access denied for user 'ippbx_admin'@'localhost' (using password: YES)。
8.0.16版本与先前的一些版本添加用户有些改变，一行指令就搞定。演示如下：
ysql> create user 'admin'@'%' identified with caching_sha2_password by 'xhai-123'
-> ;
Query OK, 0 rows affected (0.26 sec)
mysql> select user,host,authentication_string,plugin from mysql.user;
+------------------+-----------+------------------------------------------------------------------------+-----------------------+
| user | host | authentication_string | plugin |
+------------------+-----------+------------------------------------------------------------------------+-----------------------+
| admin | % | $A$005$q0{3bD]bt#>R9SeXb6Z4OS5mdwruFXD7TdiNzovrbbuI5xVxQGOSyKnL5 | caching_sha2_password |
| aplan | % | B2E0C40A5667BF1783A28667466E1399EB00FBDF | mysql_native_password |
| ippbx_admin | 127.0.0.1 | $A$005$g^8x#aXm)T7{n94IvOO8/gPE7qqaVivgEIZ.oh/nrSVG8JCNJfskJBu6j22r. | caching_sha2_password |
| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.session | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| mysql.sys | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| root | localhost | $A$005$wcJW
k,I\WN.&L+T%V4QQKnlXTx21I/fXRAaWPOco0PgVi6Md3KzdNjZKBB0 | caching_sha2_password |
+------------------+-----------+------------------------------------------------------------------------+-----------------------+
8 rows in set (0.01 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.20 sec)
mysql> exit
Bye
root@root:/b# mysql -u admin -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 42
Server version: 8.0.16 MySQL Community Server - GPL
Copyright (c) 2000, 2019, 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> exit
Bye
可以发现以不限制登录主机的方式可以成功。
数据库中有一个ippbx_admin用户，我们使用insert into 方式添加(insert into user(host,user) values("127.0.0.1","ippbx_admin");)，尝试登录却没能成功：
root@root:/b# mysql -u ippbx_admin -p
Enter password:
ERROR 1045 (28000): Access denied for user 'ippbx_admin'@'localhost' (using password: YES)
可以发现使用localhost的默认解析，而数据库中的是127.0.0.1，先前也没注意这个问题，浪费了好久时间，于是改变数据库中host字段为localhost
mysql> update user set host="localhost" where user= "ippbx_admin";
Query OK, 1 row affected (0.17 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> exit
Bye
root@root:/b# mysql -u ippbx_admin -p
Enter password:
ERROR 1045 (28000): Access denied for user 'ippbx_admin'@'localhost' (using password: YES)
发现还是没能登录，之后我们使用alter 去修改密码，注意'ippbx_admin'@'localhost' 需要与数据库保持一致
mysql> alter user 'ippbx_admin'@'localhost' identified with caching_sha2_password by 'xhai-123';
Query OK, 0 rows affected (0.13 sec)
神奇的发现可以登录了，nice
root@root:~# mysql -u ippbx_admin -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 60
Server version: 8.0.16 MySQL Community Server - GPL
Copyright (c) 2000, 2019, 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>
相关指令使用：
1、select user,host,authentication_string,plugin from mysql.user;#查看用户信息，user表中不在使用password字段，改为使用authentication_string，取值参考如下；
The caching_sha2_password and sha256_password authentication plugins provide more secure password encryption than the mysql_native_password plugin, and caching_sha2_password provides better performance than sha256_password. Due to these superior security and performance characteristics of caching_sha2_password, it is as of MySQL 8.0 the preferred authentication plugin, and is also the default authentication plugin rather than mysql_native_password.
2、GRANT ALL PRIVILEGES ON . TO 'ippbx_admin'@'localhost' WITH GRANT OPTION;#授予test账户所有权限.
PS:相同的密码在数据库中存储了不同的值，账户应该更加安全。