1.启动失败：
$ mysql -h localhost -u root -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
reason: 请记住 localhost 和 127.0.0.1 在这种情况下不是一回事：
- 如果 host 设置为
localhost，则使用套接字或管道。 - 如果 host 设置为
127.0.0.1，则客户端被迫使用TCP/IP。
如果数据库正在侦听监听连接TCP则需要mysql -h 127.0.0.1如果需要通过套接字连接到数据库，请使用mysql -h localhost
$ mysql -h 127.0.0.1 -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 21
Server version: 8.0.29 MySQL Community Server - GPL
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mysql>
