MySQL有两种主要的连接方式：
常用的还是TCP连接：
[root@mysql8 data]# mysql -h 192.168.103.67 -uroot -p
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Your MySQL connection id is 14
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mysql>
另外的一种方式就是这种unix socket的连接。在速度上比用tcp的方式更快，但只适用于mysql和应用同在一台PC上，依靠本地的.sock文件。如果不在同一台PC上，就没有办法连接了。
查看本地socket文件位置：
mysql> show variables like 'socket'\G
*************************** 1. row ***************************
Variable_name: socket
Value: /data/mysql/mysql_3306/tmp/mysql_3306.sock
1 row in set (0.01 sec)