php jquery image upload - php

Question

i have a script that uploads an image into a folder instead of saving it as a blob..
<?php
mysql_connect('localhost','root','')or die(mysql_error());
mysql_select_db('db_tourism')or die(mysql_error());
//$newname='baro.jpg';
//dir:[../../]
$uploaddir = '../../images/municipality/';
$cc=$uploaddir.$fileName;
$fileName = $_FILES['uploadfile']['name'];
$tmpName = $_FILES['userfile']['tmp_name'];
$fileSize = $_FILES['userfile']['size'];
$fileType = $_FILES['userfile']['type'];
$ext = end(explode('.', $fileName));
$newname=$fileName;//.'.'.$ext;
$file = $uploaddir .$newname; //basename($_FILES['uploadfile']['name']);
if (move_uploaded_file($_FILES['uploadfile']['tmp_name'], $file)) {
// echo "<script>alert('success:$fileName');</script>";
mysql_query("INSERT INTO `_temp-image` ( `id` , `File_name` , `path` )
VALUES (
NULL , '$fileName', '$file'
);");
echo "success";
}
else {
echo "error";
}
?>
and here is the jquery
var btnUpload=$('#uploada');
//var btnUploadTxt=$('#uploada').attr('value');
var status=$('#status');
new AjaxUpload(btnUpload, {
action: 'upload-file.php',
name: 'uploadfile',
onSubmit: function(file, ext){
if (! (ext && /^(jpg|png|jpeg|gif)$/.test(ext))){
// extension is not allowed
btnUpload.val('Only JPG, PNG or GIF files are allowed');
return false;
}
btnUpload.val('Uploading...');
},
onComplete: function(file, response){
//On completion clear the status
btnUpload.val('Upload Picture');
//Add uploaded file to list
if(response==="success"){
$('<li class="uplod" uid="_temp-image" title="click to remove ['+file+']" id="'+file+' "><span id=" '+file+' " style="font- family:calibri;font-size:10px;" >'+file+' [UPLOADED]</span></li>').appendTo('#uploaded');/ *.html('<img src="../uploaded_image/'+file+'" alt="" />'+file)*///.addClass('success');
} else{
$('<li></li>').appendTo('#uploaded').text(fi le).addClass('error');
}
}
});
it works fine i can add and delete picture... BUT my problem is handling DUPLICATE files... how to error trap if that kind of image is already uploaded??

Answer 1

Generate CRC checksum, MD5 or other hash type for image binary data and store that hash in database.
After upload - check new image checksum/hash and compare it with that stored in database.
Use md5_file function.
$md5hash = md5_file(string $filename);
Here is more: http://www.php.net/manual/en/function.md5-file.php