我尝试在给定的时间范围内从pgadmin上的表下载数据。我有下面的代码，但它不工作，我不知道为什么

ts, te=df['Timestamp'].min(), df['Timestamp'].max()
connection=psycopg2.connect('dbname=dbname user=user '
                        'password=password host=IP')
print(r'Connection to database is successful')
crsr=connection.cursor()
query="""SELECT * 
FROM public.scanning_lidar_ver2
ORDER BY timestamp ASC, scan_id ASC, range ASC
WHERE timestamp >= %(date_start)s AND timestamp <= %(date_end)s
"""
crsr.execute(query,
             {'date_start' : ts,
              'date_end':te})
df1= pd.DataFrame(crsr.fetchall())

“非常感谢您的帮助。谢谢。