Today when I tried to install mysql in my raspberry pi 2, problems happen as shown below: 
I use the command apt-get install mysql-server python-mysqldb to install mysql. Does any one know how to solve this problem?
Run this:
sudo apt-get remove --purge mysql-server mysql-client mysql-common
sudo apt-get autoremove
sudo apt-get autoclean
The issue is with mysql-common. Once you have run these commands, installation should be smooth.
I usually try finding answers from Ubuntu, if not Debian, otherwise general Linux. May or may not help.
https://askubuntu.com/questions/697805/package-mysql-server-5-5-is-not-configured-yet