select if ( mod(char_length( msgstr)+12,70) = 0, div(char_length( msgstr)+12,70), div(char_length( msgstr)+12,70)+1 ) from ngp_sms_north_interface where month(reqtime) =11

这是一条SQL语句，主要的作用是用来查询在11月份请求时间内，符合一定条件的数据。具体来说，会计算一个消息字符串的长度并进行一系列数学计算得出一个值。这个值是由字符串长度除以70后向上取整得到的，但如果除以70的余数为0，则直接取整数部分即可。最终，这个值会被查询出来并作为结果返回。

具体的操作步骤是：首先通过“month(reqtime) =11”筛选出请求时间在11月份的数据。接下来，对每一条数据中的字符串长度进行计算，计算出除以70的商和余数，并用这个商和余数得出最终的结果值。最后，将所有符合条件的结果值查询出来并返回给用户。

需要注意的是，这个SQL语句并没有对数据进行任何修改操作，只是进行了简单的查询和计算。同时，如果想要更好地了解这个语句的具体用途，还需要了解相关的数据库结构、字段含义以及业务逻辑等方面的内容。

相关问题

Exception in thread Thread-9: Traceback (most recent call last): File "C:\ProgramData\Anaconda3\lib\threading.py", line 973, in _bootstrap_inner self.run() File "C:\ProgramData\Anaconda3\lib\threading.py", line 910, in run self._target(*self._args, **self._kwargs) File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 3591, in _thread_main self.loop_forever(retry_first_connection=True) File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 1756, in loop_forever rc = self._loop(timeout) File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 1164, in _loop rc = self.loop_read() File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 1556, in loop_read rc = self._packet_read() File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 2439, in _packet_read rc = self._packet_handle() File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 3033, in _packet_handle return self._handle_publish() File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 3327, in _handle_publish self._handle_on_message(message) File "C:\ProgramData\Anaconda3\lib\site-packages\paho\mqtt\client.py", line 3570, in _handle_on_message on_message(self, self._userdata, message) File "F:\2022-2023（秋）课程\大三下\物联网开发\实验七\7.py", line 40, in on_message msgstr=msg.payload.decode('utf-8') UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa1 in position 1: invalid start byte /device01/control b'{\xa1\xb0status": 1}'

这段错误信息是关于Python中Paho MQTT客户端的一个异常。具体来说，它指出在处理MQTT消息时出现了UnicodeDecodeError，因为无法将字节串转换为UTF-8编码的字符串。可能是消息的编码不是UTF-8，或者在解码消息时发生了一些错误。需要检查代码中对消息进行解码的部分，确保正确地指定了消息的编码。

#define sensorpin 34 #define DHTPIN 2 #include <BH1750.h> BH1750 lightMeter; #include <Wire.h> #include <DHT.h> DHT dht(DHTPIN, DHT11); #include<WiFi.h> #include<PubSubClient.h> char* ssid ="17group";//此处需要改成你的wifi名称 const char*password = "hhj20011019"; //你的wifi密码 //以下四行参数勿动 const char*mqttServer = "39.106.6.44"; const int mqttPort =1886; const char*mqttUser = "iotlab"; const char*mqttPassword = "iot20121013"; WiFiClient espClient; PubSubClient client(espClient); char msg[50]; //用于存储向外发送的消息 //回调函数，topic是主题，payload就是收到的信息 void callback(char*topic, byte* payload, unsigned int length) { Serial.print("Messagearrived in topic: "); Serial.println(topic); Serial.print("Message:"); for (int i = 0; i< length; i++) { Serial.print((char)payload[i]); } Serial.println(); Serial.println("-----------------------"); } void setup() { Serial.begin(115200); WiFi.begin(ssid,password); while (WiFi.status()!= WL_CONNECTED) { delay(500); Serial.println("Connectingto WiFi.."); } Serial.println("Connectedto the WiFi network"); client.setServer(mqttServer,mqttPort); client.setCallback(callback); while (!client.connected()){ Serial.println("Connectingto MQTT..."); //请将cs202112345后面的数字替换成自己的学号 if (client.connect("cs225150340",mqttUser, mqttPassword )) { Serial.println("connected"); }else { Serial.print("failedwith state "); Serial.print(client.state()); delay(2000); } } client.subscribe("sub225150340");//请将后面的数字替换成自己的学号 { Serial.begin(115200); // Initialize the I2C bus (BH1750 library doesn't do this automatically) Wire.begin(); // On esp8266 you can select SCL and SDA pins using Wire.begin(D4, D3); // For Wemos / Lolin D1 Mini Pro and the Ambient Light shield use // Wire.begin(D2, D1); lightMeter.begin(); } } void loop() { client.loop();//此句为循环监测是否有消息过来，勿删 //以下是发送一组数据的例子,实际场景替换成读取的传感器数值 float hum = dht.readHumidity(); float temp = dht.readTemperature(); float lux = lightMeter.readLightLevel(); int soilhum =analogRead(sensorpin); snprintf(msg,50,"%.2f,%.2f,%.1f,%d",hum,temp,lux,soildhum); Serial.println(msg); //这行只是为了调试用 client.publish("pub225150430", msg); //请将后面的数字替换成自己的学号 delay(1000); } 如何接收 #define sensorpin 34 int svalue; void setup(){ Serial.begin(9600); } void loop(){ svalue=analogRead(sensorpin); Serial.println(svalue); delay(1000); } 上的数据

您可以使用 MQTT 客户端订阅相应主题，接收通过 MQTT 发布的数据。在代码中，传感器数据通过以下语句发布到 MQTT 主题 "pub225150430" 中：

client.publish("pub225150430", msg);

因此，您可以使用相同的 MQTT 客户端对象 `client`，在回调函数中订阅 "pub225150430" 主题并解析接收到的数据。

以下是示例代码：

#include <PubSubClient.h>

WiFiClient wifiClient;
PubSubClient client(wifiClient);

char receivedMsg[50];

void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived in topic: ");
  Serial.println(topic);
  Serial.print("Message:");
  
  for (int i = 0; i < length; i++) {
    receivedMsg[i] = (char)payload[i];
    Serial.print(receivedMsg[i]);
  }
  Serial.println();
  Serial.println("-----------------------");
}

void setup() {
  Serial.begin(115200);
  
  // Connect to Wi-Fi network
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Connect to MQTT broker
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
  while (!client.connected()) {
    Serial.println("Connecting to MQTT...");
    if (client.connect("cs225150340", mqttUser, mqttPassword)) {
      Serial.println("connected");
    } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }

  // Subscribe to "pub225150430" topic
  client.subscribe("pub225150430");
}

void loop() {
  client.loop();

  // Parse received message
  String msgStr = String(receivedMsg);
  float hum, temp, lux;
  int soilhum;
  sscanf(msgStr.c_str(), "%f,%f,%f,%d", &hum, &temp, &lux, &soilhum);
  
  // Do something with received data
  Serial.print("Humidity: ");
  Serial.println(hum);
  Serial.print("Temperature: ");
  Serial.println(temp);
  Serial.print("Lux: ");
  Serial.println(lux);
  Serial.print("Soil Humidity: ");
  Serial.println(soilhum);
  
  delay(1000);
}