hamidi2, you answer your own questions in every posting. Why don't you try it out or read more about the boot process with Ubuntu. Starting services in Windows is indeed
very similar to your issue. You'll only have to find out where mysql is started in the Ubuntu scripts then add your own script, just try it out, maybe write a simple script which prints hello to the screen or touches a file so that you can check if and when this file was created.
I don't have enough knowledge about Ubuntu and can't help here. Or should I say "install Slackware, then I can help you"
As for Slackware, that's how mysql is started in Slackware (in rc.M)
# Start the MySQL database:
if [ -x /etc/rc.d/rc.mysqld ]; then
. /etc/rc.d/rc.mysqld start