how to use date from my database for date.add

i use for my project this chart pygal

enter codehere

from datetime import datetime, timedelta
datey = pygal.DateY(x_label_rotation=20)
datey.add("Visits", [
    (datetime(2013, 1, 2), 300),
    (datetime(2013, 1, 12), 412),
    (datetime(2013, 2, 2), 823),
    (datetime(2013, 2, 22), 672)
])
datey.render()

but the problem is when i want to use datetime from my base i have this error TypeError: can't compare datetime.datetime to float i used this code

enter code here

@app.route('/something.svg')
def graph_something():
   datey = pygal.DateY(x_label_rotation=20,  show_dots=False)
   datey.add("Visits", 
   (temp, hum))
   return datey.render() 
   return datey_chart.render_response()