显示更多选项不适用于php和mysql

Question

我每次按点击时都会尝试添加限制但

我的HTML代码是

 <div class="media stream load-more">
    <a href="<?php echo $_SERVER['PHP_SELF']; ?>" method ='post' name = 'showmore'>
        <i class="icon-refresh shaded"></i>
            show more...
    </a>
</div>

php代码

$showvalue = 2;
if(isset($_POST['showmore'])) {
     $showvalue += 1;
}

$feeds = $db->getfeeds($showvalue);

mysql函数

public function getfeeds($showvalue){
      $stmt = $this->con->prepare("SELECT id,image,title,status,profilepic,created_at,url FROM news ORDER BY id DESC LIMIT $showvalue");
      $stmt->bind_param("s",$showvalue);
      $stmt->execute();
      $result = $stmt->get_result();

      $nrow = array();

    while ($r = $result->fetch_assoc()) {

       $nrow[] = $r;
    }
       $frow['news'] = $nrow;
    $json = str_replace("\\/", "/",json_encode($frow));
    return $json;

   }