fetch data from mysql by seperating topics and its content seperatly

        include "XXconnection.php";

        $result = mysqli_connect($host,$uname,$pwd) or die("Could not connect to database." .mysqli_error());
        mysqli_select_db($result,$db_name) or die("Could not select the database." .mysqli_error());
        $image_query = mysqli_query($result,"SELECT img_name,img_path, img_dept from image_table order by img_dept");
        while($rows = mysqli_fetch_array($image_query))
        {
            $img_name = $rows['img_name'];
            $img_src = $rows['img_path'];
            $img_dept = $rows['img_dept'];

            $name_ar = explode(', ', $img_name);
            ?>

            <?php 

                if ( $img_dept == 'mercedes') {
                    ?>
                    <div style="float:left;width:420px;border:1px solid #06F;background:#f8fdfd;padding:5px;margin-left:5px;margin-right:5px;margin-top:5px;margin-bottom: 10px;border-radius:10px 10px 0px 0px;color:#039;">   
                        <h3><?php echo $img_dept; ?></h3>

                        <?php
                        foreach ($name_ar as $value) {
                            ?>
                            <b style="font-size:14px;padding-top: 24px;">&raquo;</b> 
                            <a href="<?php echo $img_src; ?>"><?php echo $value; ?></a>

                            <?php
                        }
                        ?>
                    </div>
                    <?php
                }

?>

                <?php
            }
            ?>
        </div>


    </div>


</div>

that is my code so far. I know this is wrong. How can I seperate my content and its topic. Eg: if the Apple is a topic, then Red and Green are its content. If Banana is a topic, then Yellow, Green, Red will be its content.

So how can I fetch those seperatly under the topic with it's content.