在PHP的注释-回复系统中删除某个注释

我在php中创建了一个注释-回复系统。它类似于Facebook中的墙壁。用户写评论，然后将其发布在"墙"中。我在数据库中使用以下表来保存注释：注释（comments_id，注释，comment_date，用户，comment_hash，flash）和保存用户详细信息的表用户：用户（user_id，姓名，姓氏）。一切都很完美，唯一的问题是我无法删除某个评论。删除注释意味着在我的数据库中为此注释设置 flag=1。

每条评论上都有一个名为"删除"的链接。当用户按下删除时，一个灯箱在javascript中启动，用户通过按删除，执行"删除帖子"功能。我唯一的问题是这个函数将 flag=1 设置为我的 databe 中的所有注释，而不是我按 Delete 的某个注释。知道如何改进我的代码吗？

我使用以下函数来显示注释：

<?php
function getComments(){    
  $session_user_id = $_SESSION['user_id'];
  $comments = "";
  $sql = mysql_query("SELECT * FROM comments WHERE (`flag`=0) ORDER BY comment_date DESC LIMIT 40") or die (mysql_error());
  if(mysql_num_rows($sql) == 0){
    $comments = "<div class='each_comment'>  Write your first posts ...</div> ";
  }
  else{
    while ($row= mysql_fetch_assoc($sql)) {
  $comment_id = $row['comments_id'];
      $hash = $row['comment_hash'];
      $personal_1 = mysql_query("SELECT `user_id`, `name`, `surname`, `email`, `profile` FROM `users` WHERE `user_id`='{$row['user']}' ");
        while ($run_personal_1= mysql_fetch_assoc($personal_1)) {
          $comment_user_id = $run_personal_1['user_id'];
          $comment_user_name = $run_personal_1['name'];
          $comment_user_surname = $run_personal_1['surname'];
        }
    // displays comment that includes user's name and surname and hash
    $comments .= " $comment_user_surname   $comment_user_name   $hash";
    $comments .= ".$row['comment'].";

//---- at this point I insert a delete link , that when user presses it a javascript light box ask user if wants to delete the comment. If user press the delete button it is called the function named "deletepost".
//---- first checks if the comment is from the user that is logged in ($session_user_id) in order to have the right to delete post
  if($comment_user_id == $session_user_id){
      if(isset($_POST['submit_2'])) {
        deletepost($session_user_id, $comment_id);
        header('Location: wall.php');
      } 
  $comments .= <<<EOD
  <a href="javascript:void(0)" onclick="document.getElementById('light').style.display='block';document.getElementById('fade').style.display='block'"> <font color='grey' >Delete</font> </a>
<div id="light" class="white_content">
    <form action="$_SERVER[PHP_SELF]" method="post">
    <input type="submit" name="submit_2" value="Delete Post ">
    </form>
    <a href="javascript:void(0)" onclick="document.getElementById('light').style.display='none';document.getElementById('fade').style.display='none'"><button>Cancel</button></a>
</div>
<div id="fade" class="black_overlay"></div>             
  EOD;
  }
  }
    return $comments;   
} 
?>

我使用以下功能来发表评论：

<?php
function postComments($comment){
    $comment = mysql_real_escape_string(strip_tags($comment));
        $session_user_id = $_SESSION['user_id'];
        $random_num = rand(0, 99999999999);
        $sql = mysql_query(" INSERT INTO `comments` (comment, comment_date, user, comment_hash) VALUES ('".$comment."', now(), '$session_user_id', '$random_num') ");
    return getComments();
}
?>

我使用以下函数来删除评论。删除注释意味着我设置 flag=1，并且在显示注释的函数（函数 getComments）中，如果 flag 等于 1，则我不显示此注释：

<?php
function deletepost($comment_user_id, $comment_id){
$get_hash = mysql_query("SELECT `comment_hash` from `comments` WHERE (`user`='$comment_user_id' AND `comments_id` = '$comment_id')  ");
        while ($run_hash= mysql_fetch_assoc($get_hash)) {
            $hash = $run_hash['comment_hash'];
        }
    $sql="UPDATE `comments` SET `flag`=1 WHERE (`user`='$comment_user_id' AND `comment_hash`='$hash')";
$result=mysql_query($sql) or die("Error when trying to delete...");
}
?>