...
my $dir_to_open = "../../pics";
my $dir_to = "../../back";
while (my $row = $sth->fetchrow_hashref()) {

         for my $imgfile (map $row->{"image_$_"}, 1..4) {
           
             my $file_to_move = "$dir_to_open/$imgfile";
             
             if (-e $file_to_move && -f $file_to_move) {
               move($file_to_move, $dir_to);
               
             }
             #.. then delete the file
             unlink $file_to_move if (-e $file_to_move && -f $file_to_move);  
         
         }

       }