In Ubuntu system, using the apt-get install command to install the program, the following problems occurred.

root@1:~# sudo apt-get install mysql-server -y
sudo: unable to resolve host iZm5ej8y1b74lo14r36fvlZ
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package mysql-server

Solutions:
Sudo apt-get update sudo apt-get update
The software source is not updated, or the software source is modified,

sudo apt-get update

Second method: need to change the software source
Refer to the method of replacing the software source:

http://www.chenxm.cc/post/445.html

E: Unable to locate package mysql-server: Unable to locate package mysql-server: Unable to locate package mysql-server