<?php
if(isset($_GET['id'])){
   $id=$_GET['id'];
}

$servername = "localhost";
$username = ".............";
$password = "............";
$dbname = ".............";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {die("Connection failed: " . $conn->connect_error);}
$sql = "SELECT id,id_msg,content,topic FROM smf_cymiz WHERE id='$id'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
..
..
	}

$conn->close();
?>