I have mysql 5.5 installed, and need 5.7. Tried to update using this answer https://askubuntu.com/questions/750498/mysql-5-5-update-to-mysql-5-7/750502#750502
Then tried uninstalling 5.5 and installing from scratch following this guide https://www.digitalocean.com/community/tutorials/how-to-install-mysql-on-ubuntu-14-04
wget http://dev.mysql.com/get/mysql-apt-config_0.6.0-1_all.deb
sudo dpkg -i mysql-apt-config_0.6.0-1_all.deb
sudo apt-get update
sudo apt-get install mysql-server
On the last step I just can install 5.5 again, no 5.7:
$ sudo apt-get install mysql-server
...
The following extra packages will be installed:
libdbd-mysql-perl libdbi-perl libmysqlclient18 libterm-readkey-perl
mysql-client-5.5 mysql-common mysql-server-5.5 mysql-server-core-5.5
...
The following NEW packages will be installed:
libdbd-mysql-perl libdbi-perl libmysqlclient18 libterm-readkey-perl
mysql-client-5.5 mysql-common mysql-server mysql-server-5.5
mysql-server-core-5.5
0 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Not sure why the new configured repos for 5.7 are not being used.