转：https://www.linuxidc.com/Linux/2017-06/144805.htm

root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# sudo apt-get install MysqL-server  
Reading package lists... Done  
Building dependency tree         
Reading state information... Done  
E: Unable to locate package MysqL-server  
root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# sudo apt-get update  
root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# sudo apt-get upgrade  
root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# sudo apt-get install MysqL-server

设置MysqL允许远程访问，编辑文件/etc/MysqL/MysqL.conf.d/MysqLd.cnf
添加注释，找到bind-address = 127.0.0.1，在行首添加#号
#bind-address = 127.0.0.1
删除注释(MysqL连接数，默认100肯定不够用，设置多少看你的，我设2000)
max_connections = 2000
保存文件退出(ctrl+s)
连接MysqL：MysqL -uroot -p密码
授权：grant all on *.* to root@'%' identified by '密码' with grant option;
刷新：flush privileges;
退出MysqL：quit
重启MysqL：service MysqL restart

root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# MysqL -uroot -p密码  
MysqL: [Warning] Using a password on the command line interface can be insecure.  
Welcome to the MysqL monitor.  Commands end with ; or \g.  
Your MysqL connection id is 8  
Server version: 5.7.21-0ubuntu0.16.04.1 (Ubuntu)  
Copyright (c) 2000,2018,Oracle and/or its affiliates. All rights reserved.  
Oracle is a registered trademark of Oracle Corporation and/or its  
affiliates. Other names may be trademarks of their respective  
owners.  
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.  
MysqL> grant all on *.* to root@'%' identified by '密码' with grant option;  
Query OK,0 rows affected,1 warning (0.00 sec)  
MysqL> flush privileges;  
Query OK,0 rows affected (0.00 sec)  
MysqL> quit  
Bye  
root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install# service MysqL restart  
root@iZuf6bqngpatbwsnfpfpoqZ:/usr/lib/install#

现在在Windows下可以使用navicat远程连接Ubuntu下的MysqL服务

登录MysqL查看MysqL连接数：show variables like '%max_connections%';
如果MysqL连接数设置失效往下看：
打开文件：/lib/systemd/system/MysqL.service
在最后一行添加代码：
LimitNOFILE=65535
LimitNPROC=65535

然后执行命令：
systemctl daemon-reload

service MysqL restart再次查看MysqL链接数，修改成功