ubuntu16.04 后， 貌似mysqld在/etc/init.d下，直接執行會報mysqld不在服務中，因此開啟mysql服務失敗。
所以執行以下命令不能啟動mysql服務：
/etc/init.d/mysqld start
第一個念頭就是把mysql加入系統服務中唄。
但是，一段搗鼓之后發現。。。
ubuntu16.04后， systemctl 代替了 chkconfig。。。
下面通過 systemctl 把mysqld加入服務，執行以下命令：
1.確認mysqld在/etc/init.d/目錄下，
ls /etc/init.d/mysqld (mysqld只是 support-files/mysql.server 的一個拷貝別名文件而已)
2.查看mysqld是否在服務中
systemctl status mysqld
證明不在服務中
● mysqld.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
3.mysqld加入服務
systemctl start mysqld
4.再次查看mysqld是否在服務中
systemctl status mysqld
mysqld.service - LSB: start and stop MySQL
Loaded: loaded (/etc/init.d/mysqld; bad; vendor preset: enabled)
Active: active (running) since Tue 2019-03-19 09:32:40 PDT; 6s ago
Docs: man:systemd-sysv-generator(8)
Process: 11364 ExecStart=/etc/init.d/mysqld start (code=exited, status=0/SUCCESS)
CGroup: /system.slice/mysqld.service
├─11392 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/usr/local/mysql/data --pid-file=/usr/local/mysql/data/ubuntu.pid
└─12330 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-erro
遠程連接
mysql安裝好， 那就順便來個遠程連接的設置吧。
1.選中mysql數據庫：
mysql>use mysql;
2.查看用戶和host：
mysql>select host,user,password from user;
+-----------+------+----------+
| host | user | password |
+-----------+------+----------+
| localhost | root | |
| ubuntu | root | |
| 127.0.0.1 | root | |
| ::1 | root | |
| localhost | | |
| ubuntu | | |
+-----------+------+----------+
3.更新用戶和host信息：
mysql> update user set host='%' where user='root';
Query OK, 0 rows affected (0.00 sec)
4.確認用戶和host信息：
mysql> select user, host from user;
+------+-----------+
| user | host |
+------+-----------+
| root | % |
| root | 127.0.0.1 |
| root | ::1 |
| | localhost |
| | ubuntu |
| root | ubuntu |
+------+-----------+
6 rows in set (0.00 sec)
5.退出：
mysql> quit
6.重啟mysql：
shell>/etc/init.d/mysqld restart
7.遠程連接mysql：
我用的是MySQL Workbench