当值为零时 if 语句不起作用 (PHP)

发布于 2024-12-04 07:21:24 字数 1001 浏览 0 评论 0原文

如果我将 if($comments_count == 0) 更改为 if($comments_count == 1)，它会回显文本（如果有 1 条评论）。但恢复到 == 0 时，该命令不会被执行。我尝试在没有评论的页面上回显 $comments_count 的值，它显示 0。但是 if-else 会忽略它并且不会打印出任何内容。

这是代码：

$query = "SELECT * FROM comments WHERE id = {$set_id}";
    $all_comments_set = mysql_query($query); 
    $comments_count = mysql_num_rows($all_comments_set);

    while($comment = mysql_fetch_array($all_comments_set)) {
        if($comments_count == 0) {
            echo $comments_count;
            echo "<div class='comments'><p>There are no comments to show right now. Be the first to comment!</p></div>";
        } else {
            echo $comments_count;   
            echo "<div class='comments'>
                <p class='commenter'><a href=''>".$comment['commentAuthor']."</a></p>
                <p>".$comment['comment']."</p>
              </div>";
        }
    }

原文

If I change if($comments_count == 0) to if($comments_count == 1), it echoes out the text (if there is 1 comment). But revert back to == 0, the command doesn't get executed. I tried echoing out the value of $comments_count on a page that doesn't have a comment and it says 0. But the if-else ignores it and doesn't print out anything.

This is the code:

$query = "SELECT * FROM comments WHERE id = {$set_id}";
    $all_comments_set = mysql_query($query); 
    $comments_count = mysql_num_rows($all_comments_set);

    while($comment = mysql_fetch_array($all_comments_set)) {
        if($comments_count == 0) {
            echo $comments_count;
            echo "<div class='comments'><p>There are no comments to show right now. Be the first to comment!</p></div>";
        } else {
            echo $comments_count;   
            echo "<div class='comments'>
                <p class='commenter'><a href=''>".$comment['commentAuthor']."</a></p>
                <p>".$comment['comment']."</p>
              </div>";
        }
    }

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聚集的泪 2024-12-11 07:21:24

您需要将 if 语句移出 while 循环。由于行数为 0，mysql_fetch_array 调用将不会返回结果，并且内部 while 循环代码将不会被执行。

if($comments_count == 0) {
        echo $comments_count;
        echo "<div class='comments'><p>There are no comments to show right now. Be the first to comment!</p></div>";
} else {
    while(....){
    }
}

作为旁注，如果可以的话，您确实应该切换到使用 prepared 语句和 mysqli 或至少使用 mysql_real_escape_string 转义您的输入以防止SQL注入攻击。

You need to move the if statement out of the while loop. Since the number of rows is 0 the mysql_fetch_array call will not return a result and the inner-while loop code will not be executed.

if($comments_count == 0) {
        echo $comments_count;
        echo "<div class='comments'><p>There are no comments to show right now. Be the first to comment!</p></div>";
} else {
    while(....){
    }
}

As a side note if you can you really should switch to using prepared statements and mysqli or at least escape your input using mysql_real_escape_string to prevent SQL injection attacks.

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