1、先通過：service mysqld status 查看mysql是否啟動
（沒裝mysql service 也可通過 /etc/rc.d/init.d/mysqld status查看）
若沒啟動，則啟動mysql：service mysqld start
2、方法： 修改/etc/my.conf:
[mysqld]
datadir=/usr/local/mysql/data
socket=/var/lib/mysql/mysql.sock
[mysql.server]
user=mysql
basedir=/usr/local/mysql
If there is not currently a section called [client], add one at the bottom of the file and copy the socket= line under the [mysqld] section such as:
[client]
socket=/var/lib/mysql/mysql.sock
（注意：紅色標記部分文件路徑必須相同）
發現依舊如此，運行/etc/init.d/mysql start報錯：Starting MySQLCouldn't find MySQL manager or server
是mysqld服務沒啟，運行/usr/local/mysql/bin/mysqld_safe &