How to solve this i don't add data using by $_Post Method, but without $_POST method showing undefine variable? : if (isset($_POST['firstname']) && isset($_POST['lastname']) && isset($_POST['age'])){
		
		//Getting values
		$firstname = $_POST['firstname'];
		$lastname = $_POST['lastname'];
		$age = $_POST['age'];
		
		//Creating an sql query
		$sql = "INSERT INTO info (firstname,lastname,age) VALUES ('$firstname','$lastname','$age')";
		
		//Importing our db connection script
		require_once('connect.php');
		
		//Executing query to database
		if(mysqli_query($con,$sql)){
			echo 'Employee Added Successfully';
		}else{
			echo 'Could Not Add Employee';
		}
		
		//Closing the database 
		mysqli_close($con);
	}