อยากจะแจ้ง eror หากมีการเพิ่มไฟล์อัพโหลด ถ้าซ้ำกับ ไฟลืที่ upload ก่อนหน้า

<?php
session_start() ;

if(!session_is_registered("login_true")) {

echo "<meta http-equiv='refresh' content='0;url=index.php'>" ; 
exit() ;
}
if($_POST['btnSubmit'] == "Submit")
{
		//include("configupload.inc.php") ;
		//mysql_select_db($db) ;
}
//		mssql_select_db($db) ;
include("config.inc.php");
		if($f1!= "")
		{
				$d= date("Y-m-d");
				$picname= date("YmdHis")."1";
				$picimg = $_FILES['f1']['name'];
				// rename file
				list($filename, $filetype) = split('[.]', $picimg);  // split string
				$pic="photo/File".$picname.".".$filetype;  //rename image
				move_uploaded_file($_FILES['f1']['tmp_name'], $pic);
				$pic1 = "File".$picname.".".$filetype;
				$sql = "insert into  ApplicantDoc(IDCard,ListNox,FilesName)  values ('$_POST[IDCard]','1','$pic1')";
				mssql_query($sql);
		}

		if($f2!= "")
		{
				$d= date("Y-m-d");
				$picname= date("YmdHis")."2";
				$picimg = $_FILES['f2']['name'];
				// rename file
				list($filename, $filetype) = split('[.]', $picimg);  // split string
				$pic="photo/File".$picname.".".$filetype;  //rename image
				move_uploaded_file($_FILES['f2']['tmp_name'], $pic);
				$pic2 = "File".$picname.".".$filetype;
				$sql = "insert into  ApplicantDoc(IDCard,ListNox,FilesName) values ('$_POST[IDCard]','2','$pic2')";
				mssql_query($sql);
		}

		if($f3!= "")
		{
				$d= date("Y-m-d");
				$picname= date("YmdHis")."3";
				$picimg = $_FILES['f3']['name'];
				// rename file
				list($filename, $filetype) = split('[.]', $picimg);  // split string
				$pic="photo/File".$picname.".".$filetype;  //rename image
				move_uploaded_file($_FILES['f3']['tmp_name'], $pic);
				$pic3 = "File".$picname.".".$filetype;
				$sql = "insert into  ApplicantDoc(IDCard,ListNox,FilesName) values ('$_POST[IDCard]','3','$pic3')";
				mssql_query($sql);
		}

		if($f4!= "")
		{
				$d= date("Y-m-d");
				$picname= date("YmdHis")."4";
				$picimg = $_FILES['f4']['name'];
				// rename file
				list($filename, $filetype) = split('[.]', $picimg);  // split string
				$pic="photo/File".$picname.".".$filetype;  //rename image
				move_uploaded_file($_FILES['f4']['tmp_name'], $pic);
				$pic4 = "File".$picname.".".$filetype;
				$sql = "insert into  ApplicantDoc(IDCard,ListNox,FilesName) values ('$_POST[IDCard]','4','$pic4')";
				mssql_query($sql);
		}

		if($f5!= "")
		{
				$d= date("Y-m-d");
				$picname= date("YmdHis")."5";
				$picimg = $_FILES['f5']['name'];
				// rename file
				list($filename, $filetype) = split('[.]', $picimg);  // split string
				$pic="photo/File".$picname.".".$filetype;  //rename image
				move_uploaded_file($_FILES['f5']['tmp_name'], $pic);
				$pic5 = "File".$picname.".".$filetype;
				$sql = "insert into  ApplicantDoc(IDCard,ListNox,FilesName)  values ('$_POST[IDCard]','5','$pic5')";
				mssql_query($sql);
}
	echo "<meta http-equiv='refresh' content='2;url=uploaddetail.php'>" ; 

?>