Combining Multiple Scripts?

I've been trying to combine these two scripts for two days however, cannot for the life of me just get the dustDensity to save to my database both scripts work absolutely fine individually.

This script connects to my local wifi and saves data to a local database

#include <ESP8266WiFi.h>
#include <WiFiClient.h> 
#include <ESP8266WebServer.h>
#include <ESP8266HTTPClient.h>

int Led_OnBoard = 2;                  // Initialize the Led_OnBoard 

const char* ssid = "Lots of Security";                  // Your wifi Name       
const char* password = "Password";          // Your wifi Password

const char *host = "192.168.1.64"; //Your pc or server (database) IP, example : 192.168.0.0 , if you are a windows os user, open cmd, then type ipconfig then look at IPv4 Address.

void setup() {
  // put your setup code here, to run once:
  delay(1000);
  pinMode(Led_OnBoard, OUTPUT);       // Initialize the Led_OnBoard pin as an output
  Serial.begin(115200);
  WiFi.mode(WIFI_OFF);        //Prevents reconnection issue (taking too long to connect)
  delay(1000);
  WiFi.mode(WIFI_STA);        //This line hides the viewing of ESP as wifi hotspot
  
  WiFi.begin(ssid, password);     //Connect to your WiFi router
  Serial.println("");

  Serial.print("Connecting");
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    digitalWrite(Led_OnBoard, LOW);
    delay(250);
    Serial.print(".");
    digitalWrite(Led_OnBoard, HIGH);
    delay(250);
  }

  digitalWrite(Led_OnBoard, HIGH);
  //If connection successful show IP address in serial monitor
  Serial.println("");
  Serial.println("Connected to Network/SSID");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());  //IP address assigned to your ESP
}

void loop() {
  // put your main code here, to run repeatedly:
  HTTPClient http;    //Declare object of class HTTPClient
 
  String LdrValueSend, postData;
  int ldrvalue=analogRead(A0);  //Read Analog value of LDR
  LdrValueSend = String(ldrvalue);   //String to interger conversion
 
  //Post Data
  postData = "ldrvalue=" + LdrValueSend;
  
  http.begin("http://192.168.1.64/Nodemcu_db_record_view/InsertDB.php");              //Specify request destination
  http.addHeader("Content-Type", "application/x-www-form-urlencoded");    //Specify content-type header
 
  int httpCode = http.POST(postData);   //Send the request
  String payload = http.getString();    //Get the response payload

  //Serial.println("LDR Value=" + ldrvalue);
  Serial.println(httpCode);   //Print HTTP return code
  Serial.println(payload);    //Print request response payload
  Serial.println("LDR Value=" + LdrValueSend);
  
  http.end();  //Close connection

  delay(4000);  //Here there is 4 seconds delay plus 1 second delay below, so Post Data at every 5 seconds
  digitalWrite(Led_OnBoard, LOW);
  delay(1000);
  digitalWrite(Led_OnBoard, HIGH);
}

script 2 which reads my sensor

int dustPin = A0; // dust sensor 
int ledPin = D2;    
 
float voltsMeasured = 0;
float calcVoltage = 0;
float dustDensity = 0;
 
void setup()
{
  Serial.begin(57600);
  pinMode(ledPin,OUTPUT);
}
 
 
void loop()
{
  digitalWrite(ledPin,LOW); // power on the LED
  delayMicroseconds(280);
 
  voltsMeasured = analogRead(dustPin); // read the dust value
 
  delayMicroseconds(40);
  digitalWrite(ledPin,HIGH); // turn the LED off
  delayMicroseconds(9680);
 
  //measure your 5v and change below
  calcVoltage = voltsMeasured * (3.3 / 1024.0);
  dustDensity = 0.17 * calcVoltage - 0.1;
  Serial.println("GP2Y1010AU0F readings"); 
  Serial.print("Raw Signal Value = ");
  Serial.println(voltsMeasured); 
  Serial.print("Voltage = ");
  Serial.println(calcVoltage);
  Serial.print("Dust Density = ");
  Serial.println(dustDensity); // mg/m3
  Serial.println("");
  delay(1000);
}

Instead of saving the ldrvalue value to my database i'd like to save the dustDensity. Can anyone help please?

Do you have a version of the combined sketch?

Here's both scripts together which compile fine

#include <ESP8266WiFi.h>
#include <WiFiClient.h> 
#include <ESP8266WebServer.h>
#include <ESP8266HTTPClient.h>

int ledPin = 12;                // Initialize the Led Pin 
int dustPin = A0; // dust sensor pin 

float voltsMeasured = 0;
float calcVoltage = 0;
float dustDensity = 0;

const char* ssid = "Lots of Security";                  // Your wifi Name       
const char* password = "Password";          // Your wifi Password

const char *host = "192.168.1.64"; //Your pc or server (database) IP, example : 192.168.0.0 , if you are a windows os user, open cmd, then type ipconfig then look at IPv4 Address.

void setup() {
  // put your setup code here, to run once:
  delay(1000);
  pinMode(ledPin, OUTPUT);       // Initialize the Led_OnBoard pin as an output
  Serial.begin(115200);
  WiFi.mode(WIFI_OFF);        //Prevents reconnection issue (taking too long to connect)
  delay(1000);
  WiFi.mode(WIFI_STA);        //This line hides the viewing of ESP as wifi hotspot
  
  WiFi.begin(ssid, password);     //Connect to your WiFi router
  Serial.println("");

  Serial.print("Connecting");
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    digitalWrite(ledPin, LOW);
    delay(250);
    Serial.print(".");
    digitalWrite(ledPin, HIGH);
    delay(250);
  }

  digitalWrite(ledPin, HIGH);
  //If connection successful show IP address in serial monitor
  Serial.println("");
  Serial.println("Connected to Network/SSID");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());  //IP address assigned to your ESP
}

void loop() {
  // put your main code here, to run repeatedly:

  digitalWrite(ledPin,LOW); // power on the LED
  delayMicroseconds(280);
 
  voltsMeasured = analogRead(dustPin); // read the dust value
 
  delayMicroseconds(40);
  digitalWrite(ledPin,HIGH); // turn the LED off
  delayMicroseconds(9680);
 
  //measure your 5v and change below
  calcVoltage = voltsMeasured * (3.3 / 1024.0);
  dustDensity = 0.17 * calcVoltage - 0.1;
  Serial.println("GP2Y1010AU0F readings"); 
  Serial.print("Raw Signal Value = ");
  Serial.println(voltsMeasured); 
  Serial.print("Voltage = ");
  Serial.println(calcVoltage);
  Serial.print("Dust Density = ");
  Serial.println(dustDensity); // mg/m3
  Serial.println("");
  delay(1000);
  HTTPClient http;    //Declare object of class HTTPClient
 
  String LdrValueSend, postData;
  int ldrvalue=analogRead(A0);  //Read Analog value of LDR
  LdrValueSend = String(ldrvalue);   //String to interger conversion
 
  //Post Data
  postData = "ldrvalue=" + LdrValueSend;
  
  http.begin("http://192.168.1.64/Nodemcu_db_record_view/InsertDB.php");              //Specify request destination
  http.addHeader("Content-Type", "application/x-www-form-urlencoded");    //Specify content-type header
 
  int httpCode = http.POST(postData);   //Send the request
  String payload = http.getString();    //Get the response payload

  //Serial.println("LDR Value=" + ldrvalue);
  Serial.println(httpCode);   //Print HTTP return code
  Serial.println(payload);    //Print request response payload
  Serial.println("LDR Value=" + LdrValueSend);
  
  http.end();  //Close connection

  delay(4000);  //Here there is 4 seconds delay plus 1 second delay below, so Post Data at every 5 seconds
  digitalWrite(ledPin, LOW);
  delay(1000);
  digitalWrite(ledPin, HIGH);
}

It would be a rather filthy hack, but I suspect that changing this:

  LdrValueSend = String(ldrvalue);   //String to interger conversion

To

  LdrValueSend = String(dustDensity);   //Float to String conversion

Would do it. It is ok that your postData still says ldrValue?

Start with this sketch:

void setup()
{
  setup1();
  setup2();
}


void loop()
{
  loop1();
  loop2();
}

For the two sketches, add a New Tab using the little down-arrow menu on the right end of the tabs bar. I named them "Sketch1.ino" and "Sketch2.ino". Copy your two sketches into those new tabs. In "Sketch1.ino" change setup() to setup1() and loop() to loop1(). Similar for "Sketch2.ino". Now the combined sketch will compile.

There is one compile warning but it probably existed before the sketches were combined:

/Users/john/Documents/Arduino/sketch_oct12a/Sketch1.ino: In function 'void loop1()':
/Users/john/Documents/Arduino/sketch_oct12a/Sketch1.ino:57:71: warning: 'bool HTTPClient::begin(String)' is deprecated (declared at /Users/john/Library/Arduino15/packages/esp8266/hardware/esp8266/2.5.2/libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.h:155) [-Wdeprecated-declarations]
   http.begin("http://192.168.1.64/Nodemcu_db_record_view/InsertDB.php");              //Specify request destination

Of course if either sketch is written poorly so that, for example, loopX() doesn't return quickly, you may find that your combined sketch is not responsive. Also, if you need data to travel between sketches you may need to use a global variable or have one sketch call functions in the other sketch.

This change compiles without error:

  String DDValueSend, postData;
  extern float dustDensity;
  DDValueSend = String(dustDensity);   // float to String conversion


  //Post Data
  postData = "dustDensity=" + DDValueSend;
  http.begin("http://192.168.1.64/Nodemcu_db_record_view/InsertDB.php");              //Specify request destination
  http.addHeader("Content-Type", "application/x-www-form-urlencoded");    //Specify content-type header


  int httpCode = http.POST(postData);   //Send the request
  String payload = http.getString();    //Get the response payload

  Serial.println(httpCode);   //Print HTTP return code
  Serial.println(payload);    //Print request response payload
  Serial.println("Dust Density Value=" + DDValueSend);


  http.end();  //Close connection