遇到这种错误时，是因为使用docker 运行mysql后不能使用localhost 连接，必须使用ip 127.0.0.1 连接
参考：https://stackoverflow.com/questions/32360687/connect-to-docker-mysql-container-from-localhost
peterwong@icil-OptiPlex-7040:~$ mysql -uroot -pACahlofh -h localhost
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
(base) peterwong@icil-OptiPlex-7040:~$ mysql -uroot -pACahlofh -h 127.0.0.1
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 16
Server version: 5.7.27 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.
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