reconfigure mysql question

Question

what happens if i use this command?

sudo dpkg-reconfigure mysql-server

and more important : what happenes on my databases? are they droped?

note: when i upgrade my ubuntu 16.04 in last night , change some settings that i modified , then i can't connect to mysql when i try to connect db, i see this error:

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

i googled very much! but there isn't clear solution! i think that command can be help me to solve problem

thanks u for attention

Solution

I had problems with upgrading mysql on upgrade to 16.04. You do not have to worry about losing your data. I uninstalled mysql and installed it again and did many other (foolish) things because mysql upgrade did not work. I believe I messed it because apparmor configuration was not upgraded and then apparmor did not allow mysql to access its configuration files.

Anyway, you can use the command

sudo dpkg-reconfigure mysql-server

with no fear. On upgrade, the databases were converted to a newer format, but I lost no data and all accounts, permissions and passwords for database access were also preserved.