MySQL/Python Connection InterfaceError to Database

Question

I do not understand why I get the following connection error. I have tried many different iterations of placement of the cur = db.cursor() and cur.close(),db.close().

The loop runs fine for one cycle (and writes to the database successfully). However, in the second cycle of the loop it gives me the error below. What is wrong with my code?

#!/usr/bin/env python
import RPi.GPIO as GPIO
import time
import datetime 
import PCF8591 as ADC
import math
import Adafruit_DHT as DHT
import Adafruit_DHT
from time import strftime
DHT_TYPE = Adafruit_DHT.DHT11
#setup to write to MySQL database
import MySQLdb

#define how long to wait between readings
FREQUENCY_SECONDS      = 2

DO = 17
GPIO.setmode(GPIO.BCM)

#Variables for MySQL
db = MySQLdb.Connection(host= "localhost",
              user="mysql-user",
              passwd="password",
              db="database")

#humiture variables
Sensor = 11
humiture = 17

print('Press Ctrl-C to quit.')

def setup():
    print 'Setting up, please wait...'
    ADC.setup(0x48)
    GPIO.setup(DO, GPIO.IN)

def destroy():
    GPIO.cleanup()

while True:
    humidity, temperature = DHT.read_retry(Sensor, humiture)
    tempF = (temperature*1.8)+32
    datetimeWrite = (time.strftime("%Y-%m-%d ") + time.strftime("%H:%M:%S"))
    print datetimeWrite
    print('Temperature: {0:0.1f} F'.format(tempF))
    print('Humidity:    {0:0.1f} %'.format(humidity))
    #connect to wordpress database:
    cur = db.cursor()   
    sql = ("""INSERT INTO humiture (dateTime,temp, humidity) VALUES (%s,%s,%s)""",(datetimeWrite,tempF,humidity))
    try:
        print "Writing to database..."

        # Execute the SQL command
        cur.execute(*sql)
        # Commit your changes in the database
        db.commit()

        print "Write Complete"

    except KeyboardInterrupt:
        destroy()
        break

    cur.close()
    db.close()
    # Wait before taking another reading
    time.sleep(FREQUENCY_SECONDS)

Error message:

Traceback (most recent call last):
  File "Sensor_MySQLv2.py", line 54, in <module>
    cur.execute(*sql)
  File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 155, in execute
    charset = db.character_set_name()
_mysql_exceptions.InterfaceError: (0, '')

Answer 1

Don't close your connection each time through the loop.
Close it after the loop is finished.

Move:

db.close()

To the line after your while True: is finished executing.