This is a good idea if you want to be able to dynamically change a link and have all of your pages affected instead of changing each page one by one.
I'm not sure if a database is the best solution. Instead you could hardcode your links into an array, or something similar.
This is just one solution. Your idea of placing them in a database isn't a bad one.
$links = array( 'home' => 'home.com/home.htm', 'about' => 'aboutus.htm' );
echo '<a href="' . $links['about'] . '">About Us</a>';
Hope that helps.