ubuntu16.04 后， 貌似mysqld在/etc/init.d下，直接执行会报mysqld不在服务中，因此开启mysql服务失败。
所以执行以下命令不能启动mysql服务：
/etc/init.d/mysqld start
第一个念头就是把mysql加入系统服务中呗。
但是，一段捣鼓之后发现。。。
ubuntu16.04后， systemctl 代替了 chkconfig。。。
下面通过 systemctl 把mysqld加入服务，执行以下命令：
1.确认mysqld在/etc/init.d/目录下，
ls /etc/init.d/mysqld (mysqld只是 support-files/mysql.server 的一个拷贝别名文件而已)
2.查看mysqld是否在服务中
systemctl status mysqld
证明不在服务中
● mysqld.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
3.mysqld加入服务
systemctl start mysqld
4.再次查看mysqld是否在服务中
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
远程连接
mysql安装好， 那就顺便来个远程连接的设置吧。
1.选中mysql数据库：
mysql>use mysql;
2.查看用户和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.更新用户和host信息：
mysql> update user set host='%' where user='root';
Query OK, 0 rows affected (0.00 sec)
4.确认用户和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.重启mysql：
shell>/etc/init.d/mysqld restart
7.远程连接mysql：
我用的是MySQL Workbench