nested dictionary

from sqlalchemy import create_engine, MetaData, Table, select, func

engine = create_engine('postgresql+psycopg2://postgres:postgres@localhost:5432/cm', convert_unicode=True)
metadata = MetaData(bind=engine)
db = engine.connect()
hosts = Table('hosts', metadata, autoload=True)
results = db.execute(select({hosts}))
json_results = json.dumps([dict(r) for r in results])

results = db.execute(select({hosts}))
hosts_list =[]
for x in results:
    hosts_list.append(x[hosts.c.host_name])

hosts_dict = dict.fromkeys(hosts_list)
for key, value in hosts_dict.items():
	hosts_dict[key] = {
	{column : value for column,value in x.items()} 
	for x in results}