How do I start/stop mysql server?

I tried to find in some articles describing how to correctly start & stop mysql server.

I found this link: How to start/stop MySql server on Ubuntu 8.04 | Abhi's Blogging World

I ran this command:

/etc/init.d/mysql start 

but I see this error

ERROR 1045 (28000) Access denied for user....

After I tried this command:

sudo /etc/init.d/mysql start

I entered my password, and again I see the same error.

Next command:

sudo /etc/init.d/mysql - root -p start

results in:

ERROR 1049 (42000) Unknown database 'start'.

And when I run this command:

sudo service mysql start

MySQL server success started. Cool!

So, what's wrong with the other commands? Why do they result in error?