emlog判断文章名字是否重复，重复则提示不添加到数据库

$titles= $_POST['title'];
$check_query = mysql_query("select title from emlog_blog where title='$titles' limit 1");
if(mysql_fetch_array($check_query)){
    echo '<script>alert("您添加的文章名称已经存在。");window.history.back(-1);</script>';
    exit;
}