我收到了SQLSTATE[HY093]错误：绑定变量的数量与令牌的数量不匹配，位于comments.php的第102行以下：

<?php

/**
 * 用于处理文章的类
 */

class Comment
{
  // 属性

  /**
  * @var int 数据库中的文章ID
  */
  public $id = null;

  /**
  * @var int 文章将要/已经发布的日期
  */
  public $publicationDate = null;

  /**
  * @var string 文章的完整标题
  */
  public $title = null;

  /**
  * @var string 文章的HTML内容
  */
  public $content = null;

    /**
     * @var int 数据库中的文章ID
     */
    public $articleid = null;


  /**
  * 使用提供的数组中的值设置对象的属性
  *
  * @param assoc 属性值
  */

  public function __construct( $data=array() ) {
    if ( isset( $data['id'] ) ) $this->id = (int) $data['id'];
    if ( isset( $data['publicationDate'] ) ) $this->publicationDate = (int) $data['publicationDate'];
    if ( isset( $data['title'] ) ) $this->title = preg_replace ( "/[^.,-_'"@?!:$ a-zA-Z0-9()]/", "", $data['title'] );
    if ( isset( $data['content'] ) ) $this->content = $data['content'];
      if ( isset( $data['articleid'] ) ) $this->articleid = (int) $data['articleid'];
  }


  /**
  * 使用编辑表单的POST值设置对象的属性
  *
  * @param assoc 表单POST值
  */

  public function storeFormValues( $params ) {

    // 存储所有参数
    $this->__construct( $params );

    // 解析并存储发布日期
    if ( isset($params['publicationDate']) ) {
      $publicationDate = explode ( '-', $params['publicationDate'] );

      if ( count($publicationDate) == 3 ) {
        list ( $y, $m, $d ) = $publicationDate;
        $this->publicationDate = mktime ( 0, 0, 0, $m, $d, $y );
      }
    }
  }


  public static function getById( $id ) {
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "SELECT *, UNIX_TIMESTAMP(publicationDate) AS publicationDate FROM comments WHERE id = :id";
    $st = $conn->prepare( $sql );
    $st->bindValue( ":id", $id, PDO::PARAM_INT );
    $st->execute();
    $row = $st->fetch();
    $conn = null;
    if ( $row ) return new Comment( $row );
  }


  /**
  * 返回数据库中的所有（或一定范围内的）文章对象
  *
  * @param int 可选 要返回的行数（默认为全部）
  * @param string 可选 按照哪个列对文章进行排序（默认为"publicationDate DESC"）
  * @return Array|false 一个包含两个元素的数组：results => array，文章对象的列表；totalRows => 文章的总数
  */

    public static function getList( $art=1, $order="publicationDate DESC", $numRows=10000 ) {
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "SELECT SQL_CALC_FOUND_ROWS *, UNIX_TIMESTAMP(publicationDate) AS publicationDate FROM comments WHERE articleid = :art 
        ORDER BY " . mysql_escape_string($order) . " LIMIT :numRows";

    $st = $conn->prepare( $sql );
    $st->bindValue( ":art", $art, PDO::PARAM_INT );
    $st->execute();
    $list = array();

    while ( $row = $st->fetch() ) {
      $comments = new Comment( $row );
      $list[] = $comment;
    }
  }


  /**
  * 将当前的文章对象插入到数据库中，并设置其ID属性。
  */

  public function insert() {

    // 插入文章
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "INSERT INTO comments ( publicationDate, title, content, articledid ) VALUES ( FROM_UNIXTIME(:publicationDate), :title, :content, :articleid )";
    $st = $conn->prepare ( $sql );
    $st->bindValue( ":publicationDate", $this->publicationDate, PDO::PARAM_INT );
    $st->bindValue( ":title", $this->title, PDO::PARAM_STR );
    $st->bindValue( ":content", $this->content, PDO::PARAM_STR );
    $st->bindValue( ":articleid", $this->articleid, PDO::PARAM_STR );
    $st->execute();
    $this->id = $conn->lastInsertId();
    $conn = null;
  }


  /**
  * 在数据库中更新当前的文章对象。
  */

  public function update() {

    // 更新文章
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $sql = "UPDATE comments SET publicationDate=FROM_UNIXTIME(:publicationDate), title=:title, summary=:summary, content=:content, articleid=:articleid,imageExtension=:imageExtension WHERE id = :id";
    $st = $conn->prepare ( $sql );
    $st->bindValue( ":publicationDate", $this->publicationDate, PDO::PARAM_INT );
    $st->bindValue( ":title", $this->title, PDO::PARAM_STR );
    $st->bindValue( ":content", $this->content, PDO::PARAM_STR );
      $st->bindValue( ":articleid", $this->articleid, PDO::PARAM_STR );
    $st->bindValue( ":id", $this->id, PDO::PARAM_INT );
    $st->execute();
    $conn = null;
  }


  /**
  * 从数据库中删除当前的文章对象。
  */

  public function delete() {


    // 删除文章
    $conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );
    $st = $conn->prepare ( "DELETE FROM comments WHERE id = :id LIMIT 1" );
    $st->bindValue( ":id", $this->id, PDO::PARAM_INT );
    $st->execute();
    $conn = null;
  }

}

?>