Transfer Beaker Memcache into SqlAlchemy (MySQL)

Question

I work with Flask and want to create some user sessions working on database.

Thanks to some help I found this snippet http://flask.pocoo.org/snippets/61/

from flask import Flask, request
from beaker.middleware import SessionMiddleware

session_opts = {
'session.type': 'ext:memcached',
'session.url': '127.0.0.1:11211',
'session.data_dir': './cache',
}

app = Flask(__name__)       

@app.route('/')
def index():
   session = request.environ['beaker.session']
    if not session.has_key('value'):
    session['value'] = 'Save in session' 
    session.save()   
    return "Session value set."
else:
    return session['value']

if __name__ == '__main__':
    app.wsgi_app = SessionMiddleware(app.wsgi_app, session_opts)
    app.run(debug=True)

I have problems converting the example above into working SQLAlchemy running code. Not easy to find a tutorial for that. All I've got is http://beaker.readthedocs.org/en/latest/modules/sqla.html#module-beaker.ext.sqla

I know that session.type and url should be changed for ext:sqla and valid sql string to the database. But what's next?