delete photo script gives errors in php and mysql - php

Question

hi guys im trying to create a ajax delete script for my gallery but it doesn't seem to be deleting, instead it gives the following errors.
Warning: Division by zero in /opt/lampp/htdocs/project/others/delete_photo.php on line 20
Warning: unlink(): No such file or directory in /opt/lampp/htdocs/project/others/delete_photo.php on line 20
the delete script is as follows:
<?php
require $_SERVER["DOCUMENT_ROOT"].'/project/includes/dbconfig.inc.php';
$session= htmlentities($_SESSION['uname']);
$sess_uname= stripslashes($session);
$id0= htmlentities($_POST['id']);
$id= stripslashes($id0);
$sql="DELETE FROM photos WHERE id=':id' LIMIT 1";
$stmt=$conn->prepare($sql);
$stmt->bindparam(":id",$id);
$stmt->execute();
$sql1 = "SELECT * FROM photos WHERE user=':session' LIMIT 30";
$stmth=$conn->prepare($sql1);
$stmth->bindparam(":session",$sess_uname);
$stmth->execute();
$dir="user/$sess_uname";
$count0=$stmth->fetch(PDO::FETCH_ASSOC);
$count=count($count0);
$row1 = $stmth->fetch(PDO::FETCH_ASSOC);
if ($count>0) {
unlink($dir/$row1['filename']);
}
/*if (isset($_SESSION['app'])&&$_SESSION['uname']!="") {
header("location: ../home.php?u={$_SESSION['uname']}");
} else {
header("location: ../index.php?usernotfound?id=017");
}
*/
the ajax logic is as follows:
$("button.delete_photo").click(function(){
var del_id = $(this).attr('id');
var del_attr=$(this).attr('attr');
$.post("others/delete_photo.php",
{id:del_id},function(data){
$("."+del_id).slideUp('slow', function() {$(this).remove(data);});
}
);
});

Answer 1

Starting from the very beginning:
1)
echo this and see what you get? Are you getting the desired/expected name?
echo $session= htmlentities($_SESSION['uname']);
If so, echo this as well:
$sess_uname= stripslashes($session);
2) Similarly, if you're getting a expected result by echoing from:
$id0= htmlentities($_POST['id']);
This means your first query should work.
Now, the query below works if you have already got a expected result from 1)
$sql1 = "SELECT * FROM photos WHERE user=':session' LIMIT 30";
3) This is not the correct way to assign a directory.
$dir="user/$sess_uname";
Rather use the proper concatenation like:
$dir= "user" . "/" . $sess_uname;
4) If for all that works above, this is also incorrect. Either use $_SERVER['DOCUMENT_ROOT'] to construct absolute paths beginning with the root of your website, or else use relative paths, The line written below is the reason you're getting the Warning: Division by zero:
unlink($dir/$row1['filename']);
Which rather should have been:
unlink($dir . "/" . $row1['filename']);
But that is only if $row1 is working, which at the moment clearly is not.

Answer 2

Change this line
unlink($dir/$row1['filename']);
to
unlink($dir.'/'.$row1['filename']);
Because instead of providing directory structure, you are dividing the value.

Answer 3

finally found the solution, the problem was with the sql syntax.
previously it was like:
$sql="DELETE FROM photos WHERE id=':id' LIMIT 1";
$sql1 = "SELECT * FROM photos WHERE user=':session' LIMIT 30";
i took out the single quotes for id as it was an integer and now it works like a charm.
now my code looks like this:
$sql="DELETE FROM photos WHERE id=:id LIMIT 1";
$sql1 = "SELECT * FROM photos WHERE id=:id LIMIT 1";