Once you installed MySQL, you might need to set the MySQL root password to protect your DB. Actually how to do that?
Just type the following command on your terminal
[root@techkaki] # mysqladmin -u root password NEWPASSWORD
However, if you want to change (or update) a root password, then you need to use following command
[root@techkaki] # mysqladmin -u root -p 'oldpassword' password newpass
Eg:
[root@techkaki] # mysqladmin -u root -p 'abcdef' password '123456'