Question

我的代码应根据要求显示特定类别和品牌的产品。例如，我选择了Apple品牌，它仅显示Apple产品。但是它不起作用，回顾了Stackoverflow的一半内容以及PHP和MySQL文档。这是一个错误：

Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, bool given in C:\xampp\htdocs\shop\view_cat.php on line 126

第126行是：

if (mysqli_num_rows($result) > 0 ){

也许我需要用foreach代替do-while循环？版本PHP 7.3.5，MariaDB 10.1.37

<?php

    if (!empty($cat) && !empty($type)) {
        $querycat = "AND brand='$cat' AND type_towara='$type'";
     } else {
         if (!empty($type)) {
             $querycat = "AND type_towara='$type'";
         } else {
             $querycat = "";
         }
     }

        $result = mysqli_query($link,"SELECT * FROM table_products $querycat ORDER BY $sorting");
        if (mysqli_num_rows($result) > 0 ){
            $row = mysqli_fetch_array($result);
            do {
                if ($row["image"] != "" && file_exists("./uploads_images/".$row["image"])){
                    $img_path = './uploads_images/'.$row["image"];
                    $max_width = 150;
                    $max_height = 150;
                    list($width, $height) = getimagesize($img_path);
                    $ratioh = $max_height/$height;
                    $ratiow = $max_width/$width;
                    $ratio = min ($ratioh, $ratiow);
                    $width = intval($ratio*$width);
                    $height = intval($ratio*$height);
                }else{
                    $img_path = "/shop/images/noimages80x70.png";
                    $width = 80;
                    $height = 70;
                }
                echo (' 
                    <li>
                    <div class="block-images-list">
                    <img src="'.$img_path.'" width="'.$width.'" height="'.$height.'"/>
                    </div>

                    <ul class="reviews-and-counts-list">
                    <li><img src="/shop/images/eye-icon.png"/><p>0</p></li>
                    <li><img src="/shop/images/comment-icon.png"/><p>0</p></li>
                    </ul>

                    <p class="style-title-list"><a href="">'.$row["title"].'</a></p>

                    <a class="add-cart-style-list"></a>
                    <p class="style-price-list"><strong>'.$row["price"].'</strong> dollars.</p>
                    <div class="style-text-list">
                    '.$row["mini_description"].'
                    </div>
                    </li>
                ');
        }
        while ($row = mysqli_fetch_array($result));
        }
    ?>

Mysqli_num_rows（）期望参数1为mysqli_result，bool给出。到底是怎么回事？

0 个答案: