Problem inserting data from an ESP32 board to a MySQL database using Arduino IDE and XAMPP

Projects Programming
1

Hello everyone,
I am having a problem sending data from an ESP32 board to a MySQL database by inserting it into a table.
Unfortunately, the PHP script does not seem to read the data received from the ESP32 board to insert it into the database table. Here are my codes and the result obtained on the serial monitor in Arduino IDE:

Arduino code:

#include <WiFi.h>
#include <HTTPClient.h>

String URL = "http://192.168.1.**/dht11_project/test_data.php";

const char* ssid = "**************";
const char* password = "******";

int temperature = 50;
int humidity = 50;

void setup() {
  // put your setup code here, to run once:
 Serial.begin(115200);
 connectWiFi();
 
}

void loop() {
  // put your main code here, to run repeatedly:
 if(WiFi.status() != WL_CONNECTED) {
  connectWiFi();
 }

 String postData = "temperature=" + String(temperature) + "&humidity=" + String(humidity);
 
 HTTPClient http;
 http.begin(URL);

 int httpCode = http.POST(postData);
 String payload = http.getString();
  
  http.addHeader("Content-Type", "application/x-www-form-urlencoded");
  
  Serial.print("URL : "); Serial.println(URL);
  Serial.print("Data : "); Serial.println(postData);
  Serial.print("httpCode : "); Serial.println(httpCode);
  Serial.print("payload : "); Serial.println(payload);
  Serial.println("------------------------------------------------------");
}

void connectWiFi(){
  
  WiFi.mode(WIFI_OFF);
  delay(1000);
  
  WiFi.mode(WIFI_STA);

  WiFi.begin(ssid, password);
  Serial.println("Connecting to WiFi");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.print("connected to : "); Serial.println(ssid);
  Serial.print("IP address : "); Serial.println(WiFi.localIP());
}

PHP code :

<?php

$hostname = "localhost";
$username = "root";
$password = "";
$database = "sensor_db";

$conn = mysqli_connect ($hostname, $username, $password, $database);

if (!$conn) {
	die("Connection failed: " . mysqli_connect_error());
}

echo "Database connection is OK<br>";

if(isset($_POST["temperature"]) && isset($_POST["humidity"])) {

	$t = $_POST["temperature"];
	$h = $_POST["humidity"];


	$sql = "INSERT INTO dht11 (temperature, humidity) VALUES (".$t.", ".$h.")";

	if (mysqli_query($conn, $sql)) {
		echo "New record created successfully";
	} else {
		echo "Error: " . $sql . "<br>" . mysqli_error($conn);
	}
}
?>

Result :

Connecting to WiFi
..connected to : ***********
IP address : 192.168.1.**
URL : http://192.168.1.**/dht11_project/test_data.php
Data : temperature=50&humidity=50
httpCode : 200
payload : Database connection is OK

Any help or suggestions to resolve this issue would be greatly appreciated.

Thanks in advance !

2

Maybe post in English ?

4

Post mis dans la mauvaise section, on parle anglais dans les forums généraux. ➜ déplacé vers le forum francophone.

Merci de prendre en compte les recommandations listées dans "Les bonnes pratiques du Forum Francophone".

5

Moved back to the English part of the forum as OP has changed the language to English.

6

First of all, this allows SQL Injection attacks. In general, don't do string concatenation with user input to create SQL commands.

	$sql = "INSERT INTO dht11 (temperature, humidity) VALUES (".$t.", ".$h.")";

In this case, because the two values are just numbers, you can parse and validate to make sure that is the case -- each value is a single number.

For your actual question, put all the headers with addHeader before the POST

7

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