How can I integrate the stylesheet on database using roots?

Integrate stylesheet on database so changes can be applied directly from admin?

I don’t think you can. Well, you can but you’d be missing half the goodness of roots. Since roots uses Grunt to compile Less into CSS, the admin editor would only ever see the compiled CSS. By default it’s minified but you could certainly turn that off. If you ever edit and recompile from the less source files again though, any manual edits to your site’s css would be wiped out. I think you have two paths if editing CSS via the WP admin is important.

  1. Compile the CSS one last time, turning off the minification (part of the uglify task in Gruntfile.js). Copy all of that CSS into the theme’s style.css and point /lib/scripts back at that styles.css file
  2. Add another style sheet to your theme and make that one accessible in the wp-admin. Make sure it goes into your template after the main.min.css so that it can be used to override styles from there.