为什么mysql Insert命令在python中对我不起作用？

Question

The query is correct but I do not understand why it cannot be added into my database. Please help me thanks. I am a beginner and I can hardly debug this one.

    def callback(channel):
    print("\nflame detected\n")

GPIO.add_event_detect(channel, GPIO.BOTH, bouncetime=300)#pin if HIGH or LOW
GPIO.add_event_callback(channel, callback)       


while True:

    db = MySQLdb.connect(host="localhost", user="root", passwd="password", db="results")
    #create a cursor for the select
    cur = db.cursor()
    result = instance.read()
    if result.is_valid():
        print("Last valid input: " + str(datetime.datetime.now()))
        print("Temperature: %d C" % result.temperature)
        print("Temperature: %d F" % ((result.temperature*9/5)+32))
        print("Humidity: %d %%" % result.humidity)

        cel = str(result.temperature)
        far = str((result.temperature*9/5)+32)
        hum = str(result.humidity)
        fla = "No Flame"




    #execute an sql query
    sql = "INSERT INTO res(celsius,fahrenheit,humidity,flame) VALUES('"+cel+"','"+far+"','"+hum+"','"+fla+"')"
    cur.execute(sql)

        # close the cursor
    cur.close()

    # close the connection
    db.close ()
    time.sleep(1)

Answer 1

You can try ...

sql = "INSERT INTO res(celsius,fahrenheit,humidity,flame) VALUES(%s,%s,%s,%s)"
data = (cel, far, hum, fla)

Specifying the need values and making it clearer, also you're missing the db.commit()

cur.execute(sql, data) with this you have executed the command also passing it's value to sql

then after that you can commit your db.

db.commit()

then close the connection.