function clean_db()
{
	$query = "select clean_date from tbl_last_clean";
	$result = mysql_query($query);
	$row = mysql_fetch_row($result);

	if ( empty($row[0]) )
	{
		$query = "insert into tbl_last_clean(clean_date) values('".time()."')";
		$result = mysql_query($query);
		
		if ($result) 
			return;
		else
			echo '[{error:"Error during db clean."}]'; exit;

	}
	else
	{
		if( date("d",$row[0]) != date("d",time()) )
		{
			$query = "delete from tbl_link where expire < '".time()."'";
			$result = mysql_query($query);
			
			$query = "update tbl_last_clean set clean_date = '".time()."'";
			$result = mysql_query($query);
		}
		else
			return;
	}
	
}