Thanks guys my work is done related with thumbnail. Here's the code for this:-
$img_dir = 'image/';
$image_name = $info['image'];
if(is_file($img_dir."".$image_name)){
echo "<td>"."<img src=\"image/". $info['image'] . "\" alt=\"\" width=100 heigth=50 />"."</td>";
}else{
echo "<td> </td>";
through this code, if there is no image in database then it display blank in table.