Question

我有一个元组如下

data = ({'weather station name': 'Substation', 'wind': '6 km/h', 'barometer': '1010.3hPa', 'humidity': '42%', 'temperature': '34.5 C', 'place_id': '001D0A00B36E', 'date': '2016-05-10 09:48:58'})

我正在尝试使用以下代码将上述元组中的值推送到postgres表：

try:                                                                                                                                                                                                         
    con = psycopg2.connect("dbname='WeatherForecast' user='postgres' host='localhost' password='****'")                                                                                                         
    cur = con.cursor()                                                                                                                                                                                                  
    cur.executemany("""INSERT INTO weather_data(temperature,humidity,wind,barometer,updated_on,place_id) VALUES (%(temperature)f, %(humidity)f, %(wind)f, %(barometer)f, %(date)s, %(place_id)d)""", final_weather_data)
    ver = cur.fetchone()                                                                                                                                                                                                
    print(ver)                                                                                                                                                                                                          

except psycopg2.DatabaseError as e:                                                                                                                                                                                     
    print('Error {}'.format(e))                                                                                                                                                                                         
    sys.exit(1)

finally:                                                                                                                                                                                                                

  if con:                                                                                                                                                                                                             
     con.close()

DB中每个字段的数据类型如下： id serial NOT NULL，

temperature double precision NOT NULL,
humidity double precision NOT NULL,
wind double precision NOT NULL,
barometer double precision NOT NULL,
updated_on timestamp with time zone NOT NULL,
place_id integer NOT NULL,

当我运行代码使用psycopg2将数据推送到postgres表时，它会引发错误"ValueError: unsupported format character 'f'"

我希望问题在于格式化。我使用的是Python3.4

Answer 1

查看documentation：

变量占位符必须始终为%s，即使其他占位符（例如整数的%d或浮点数的%f）看起来更合适：
>>> cur.execute("INSERT INTO numbers VALUES (%d)", (42,)) # WRONG
>>> cur.execute("INSERT INTO numbers VALUES (%s)", (42,)) # correct

虽然，您的SQL查询包含所有类型的占位符：

"""INSERT INTO weather_data(temperature,humidity,wind,barometer,updated_on,place_id) 
   VALUES (%(temperature)f, %(humidity)f, %(wind)f, %(barometer)f, %(date)s, %(place_id)d)"""

使用psycopg2将数据导入postgres表时出现值错误

1 个答案: