How do I start MySql?

[JoJoRaz]

I try to start MySql with the command: 'mysql start'. I get the error message: "Can't connect to MySql server through socket '/var/lib/mysql/mysql.sock' (2).
The regular path to MySql in Linux doesn't seem to apply to YDL.
What does all this mean? What must I do to start MySql in YDL?