PHP和MySQL：mysqli_num_rows（）期望参数1为mysqli_result，给定布尔值[重复]

Question

这个问题已经在这里有了答案 ：

mysqli_fetch_assoc（）期望参数/调用成员函数bind_param（）错误。如何获取并修复实际的mysql错误？ （1个答案）

5年前关闭。

我正在尝试集成HTML Purifier
http://htmlpurifier.org/来过滤我的用户提交的数据，但是下面出现以下错误。我想知道如何解决这个问题？

我收到以下错误。

on line 22: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given

第22行是。

if (mysqli_num_rows($dbc) == 0) {

这是PHP代码。

if (isset($_POST['submitted'])) { // Handle the form.

    require_once '../../htmlpurifier/library/HTMLPurifier.auto.php';

    $config = HTMLPurifier_Config::createDefault();
    $config->set('Core.Encoding', 'UTF-8'); // replace with your encoding
    $config->set('HTML.Doctype', 'XHTML 1.0 Strict'); // replace with your doctype
    $purifier = new HTMLPurifier($config);


    $mysqli = mysqli_connect("localhost", "root", "", "sitename");
    $dbc = mysqli_query($mysqli,"SELECT users.*, profile.*
                                 FROM users 
                                 INNER JOIN contact_info ON contact_info.user_id = users.user_id 
                                 WHERE users.user_id=3");

    $about_me = mysqli_real_escape_string($mysqli, $purifier->purify($_POST['about_me']));
    $interests = mysqli_real_escape_string($mysqli, $purifier->purify($_POST['interests']));



if (mysqli_num_rows($dbc) == 0) {
        $mysqli = mysqli_connect("localhost", "root", "", "sitename");
        $dbc = mysqli_query($mysqli,"INSERT INTO profile (user_id, about_me, interests) 
                                     VALUES ('$user_id', '$about_me', '$interests')");
}



if ($dbc == TRUE) {
        $dbc = mysqli_query($mysqli,"UPDATE profile 
                                     SET about_me = '$about_me', interests = '$interests' 
                                     WHERE user_id = '$user_id'");

        echo '<p class="changes-saved">Your changes have been saved!</p>';
}


if (!$dbc) {
        // There was an error...do something about it here...
        print mysqli_error($mysqli);
        return;
}

}

Answer 1

$dbc返回假。您的查询中有一个错误：

SELECT users.*, profile.* --You do not join with profile anywhere.
                                 FROM users 
                                 INNER JOIN contact_info 
                                 ON contact_info.user_id = users.user_id 
                                 WHERE users.user_id=3");

Raveren已描述了一般的解决方法。