When setting your image, you can check if the value is empty before setting the image. If its empty, you put the name of a placeholder image instead. Your image code looks like this:
php:
<img src="<?php echo $row_DetailRS1['photo1']; ?>" />
Try something like this:
php:
<img src="<?php echo (strlen($row_DetailRS1['photo1']) > 0)?$row_DetailRS1['photo1']:"{defaultimagename}"; ?>" />
note, you should replace {defaultimagename} with an image you want to be displayed for images that don't have anything stored. This code checks if the length of the name is greater than 0 and if it is then it uses that name otherwise, it uses the default image.
