我正在工作的树莓皮4b和有一个bme680空气质量传感器连接起来。我每秒钟读取一次数据，然后写入mysql数据库。
如果空气质量、温度等超出最佳范围，我想发出警报。我遇到的问题是传感器每秒读取一个读数，因此如果我尝试建立警报，它会每秒关闭，直到范围恢复到最佳状态。我想知道只有在值超出范围时如何发出警报。

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries

# SPDX-License-Identifier: MIT

import time
import board
from busio import I2C
import adafruit_bme680
import subprocess
import mysql.connector
from datetime import datetime

# SQL Setup

mydb = mysql.connector.connect(
  host="localhost",
  user="some_user",
  password="some_pass",
  database="some_db"
)

# Create library object using our Bus I2C port

i2c = I2C(board.SCL, board.SDA)
bme680 = adafruit_bme680.Adafruit_BME680_I2C(i2c, debug=False)

# change this to match the location's pressure (hPa) at sea level

bme680.sea_level_pressure = 1013.25

# You will usually have to add an offset to account for the temperature of

# the sensor. This is usually around 5 degrees but varies by use. Use a

# separate temperature sensor to calibrate this one.

temperature_offset = -1

while True:
    now = datetime.now()
    formatted_date = now.strftime('%Y-%m-%d %H:%M:%S')

# print("\nTemperature: %0.1f C" % (bme680.temperature + temperature_offset))

# print("Gas: %d ohm" % bme680.gas)

# print("Humidity: %0.1f %%" % bme680.relative_humidity)

# print("Pressure: %0.3f hPa" % bme680.pressure)

# print("Altitude = %0.2f meters" % bme680.altitude)

# print (formatted_date)

    tmp = (bme680.temperature + temperature_offset)
    real_temp = (tmp * 1.8) + 32

# print(real_temp)

    gas = (bme680.gas)
    humid = (bme680.relative_humidity)
    pres = (bme680.pressure)
    mycursor = mydb.cursor()
    sql = "INSERT INTO data (Temperature, Gas, Humidity, Pressure, DT) VALUES (%s, %s, %s, %s, %s)"
    val = (real_temp, gas, humid, pres, formatted_date)
    mycursor.execute(sql, val)
    mydb.commit()

## if ( tmp > 19 ):

## subprocess.call(['python3', 'alert.py'])

# else:

# print ("nothing to do")

    time.sleep(1)

这是我的密码。我再也不想给我的朋友打电话了 alert.py 每过一秒，服务器就会发出警报，我希望在温度降到19摄氏度以下时发出一次警报。
谢谢您