PHP - How Can I Retrieve Different Rows Of Data From Mysql Database Table And Display Them In Multi-item Bootstrap Carousel?

I've been working on developing a CMS blog and now I'm trying to create a slideshow wit Bootstrap Carousel on the homepage to present the dynamic content (images + text) using the data from table 'posts'.

I tested this code, and it only presents one post. I mean, It's not possible to go to the next slide. I want to show all the posts on the slides.

*The DB connection is already on the includes. The connection was written on a small file called DB.php

Home.php

<header>
          <div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
                  <ol class="carousel-indicators">
                    <li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
                    <li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
                    <li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
                  </ol>
                  <div class="carousel-inner" role="listbox">
              <?php
              // The default SQL query
                  $sql = "SELECT * FROM posts ORDER BY id desc";
                  $stmt = $ConnectingDB->query($sql);
                    while ($DataRows = $stmt->fetch()) {
                      $Id = $DataRows["id"];
                      $PostTitle = $DataRows["title"];
                      $Image = $DataRows["image"];
                      $PostText = $DataRows["post"];
              ?>
                    <!-- Slide -->
                    <div class="carousel-item active" style="background-image: url('uploads/<?php echo $Image; ?>')">
                      <div class="carousel-caption">
                        <div class="card-body black">
                          <h3 class="large-mistral-white"><?php echo $PostTitle; ?></h3>
                          <p class="small-times-white"><?php echo $PostText; ?></p>
                        </div>
                      </div>
                    </div>
                    <?php } ?>
                  </div>
                  <a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
                    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
                    <span class="sr-only">Previous</span>
                  </a>
                  <a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
                    <span class="carousel-control-next-icon" aria-hidden="true"></span>
                    <span class="sr-only">Next</span>
                  </a>
                </div>
        </header>

DB.php

<?php

$DSN='mysql:host = localhost; dbname=everybody_blog';
$ConnectingDB = new PDO($DSN,'root','');
?>

CREATE TABLE IF NOT EXISTS `contacts` (
`contact_id` int(10) NOT NULL AUTO_INCREMENT,
`firstname` varchar(255) NOT NULL,
`lastname` varchar(255) NOT NULL,
`company` varchar(255) NOT NULL,
`cell_no` text NOT NULL,
PRIMARY KEY (`contact_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ;

CREATE TABLE IF NOT EXISTS `users` (
`user_id` int(11) NOT NULL AUTO_INCREMENT,
`users_name` varchar(30) NOT NULL,
`uname` varchar(30) NOT NULL,
`u_pass` varchar(60) NOT NULL,
`utype` varchar(30) NOT NULL,
`timezone` varchar(30) NOT NULL,
`uapi_user` varchar(30) NOT NULL,
`uapi_pass` varchar(60) NOT NULL,
PRIMARY KEY (`user_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=20 ;

<?php
if (isset($_POST['submit'])){
    //form has been submitted1
    $firstname  = trim($_POST['firstname']);
    $lastname   = trim($_POST['lastname']);
    $company    = trim($_POST['company']);
    $cellno = trim($_POST['cell_no']);

    if($firstname == ''){
        echo '<div class="alert alert-danger">First Name is not Valid!</div>';
        exit;
    }elseif($lastname == ''){   
        echo '<div class="alert alert-danger">Last Name is not Valid!</div>';
        exit;
    }elseif($company == ''){    
        echo '<div class="alert alert-danger">Company is not Valid!</div>';
        exit;
    }elseif($cellno == ''){ 
        echo '<div class="alert alert-danger">Cellphone Number is not Valid!</div>';
        exit;

    }else{

        $query = "Select cell_no from contacts where cell_no = '".$cellno."' ";
        $result = mysql_query($query);
        if (!mysql_num_rows($result)) {

        $sql = "INSERT INTO contacts(firstname, lastname, company, cell_no)
                            values('{$firstname}','{$lastname}', '{$company}', '{$cellno}')";
        $result = mysql_query($sql);
        confirm_query($result);

        //echo '<div class="alert alert-success">Successfully added.</div>';
        //exit;
        ?>
                    <script type="text/javascript">
            window.location = "contact_list.php";
        </script>
    <?php
    }
    else{

        echo '<div class="alert alert-danger">Username. already exist!.</div>';
        echo '<p><a href="new_contact.php" class="btn btn-success"> Back </a></p>';
        exit;

    }}

}else{
    $firstname  = "";
    $lastname   = "";
    $company    = "";
    $cellno = "";
}

?>