sql_dataframe_hexes.py

from sqlalchemy import create_engine  
import psycopg2

conn = psycopg2.connect("postgres://postgres:mypassword@db:5432/postgres")
sql = """with q as (
            select q.id, q.Q_socio, st_setsrid(q.wkb_geometry, 4326) geom from quartiers_sociologiques q
        ), p as (
            select st_setsrid(wkb_geometry, 4326) geom, price from sqfeet_properties as p
        )
        select q.id, q.Q_socio, q.geom, sum(p.price) sum_price from q, p 
        where q.geom && p.geom and st_intersects(q.geom, p.geom) 
        group by q.id, q.Q_socio, q.geom
        """
df = geopandas.GeoDataFrame.from_postgis(sql, conn, geom_col="geom")  
df.plot("sum_price", legend="True")