一、问题起因：
在修改了MySQL8.0.35的用户表mysql.user中的root用户口令后（authentication_string 字段值），退出mysql再进入后，使用 show databases/show tables，就出现一下错误：
mysql> show databases;
ERROR 1449 (HY000): The user specified as a definer ('mysql.infoschema'@'localhost') does not exist
mysql> use mysql
Database changed
mysql> show tables;
ERROR 1449 (HY000): The user specified as a definer ('mysql.infoschema'@'localhost') does not exist
二、解决办法：
总体办法就是给 mysql.infoschema 用户添加权限。
MySQL8.0 之后，不支持使用 grant 时隐式地创建用户，必须先创建用户，再授权。代码如下：
mysql> create user 'mysql.infoschema'@'%' identified by '密码';
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to 'mysql.infoschema'@'%';
Query OK, 0 rows affected (0.01 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
在使用show databases/ show tables，就正常了。
mysql> show databases;
Database
information_schema
mysql
performance_schema
sys
4 rows in set (0.01 sec)
mysql> show tables;
Tables_in_mysql
columns_priv
component
db
default_rolese
ngine_cost
func
general_log
global_grants
gtid_executed
help_category
help_keyword
help_relation
help_topic
innodb_index_stats
innodb_table_stats
password_history
plugin
procs_priv
proxies_priv
replication_asynchronous_connection_failover replication_asynchronous_connection_failover_managed
role_edges
server_cost
servers
slave_master_info
slave_relay_log_info
slave_worker_info
slow_log
tables_priv
time_zone
time_zone_leap_second
time_zone_name
time_zone_transition
time_zone_transition_type
user
35 rows in set (0.00 sec)
