子菜单未显示

Question

我已经创建了一个数据来自数据库的菜单。我需要看到第二级和第三级菜单，但问题是子菜单没有显示。只显示第一级。

我添加了css和php代码。

Plz检查菜单图片：

php代码：

<?php

function display_children($parent, $level) {
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "nfs";
    $conn = new mysqli($servername, $username, $password, $dbname);

   $result = mysqli_query($conn, "SELECT a.cat_id, a.product, a.category_link, Deriv1.Count FROM `category` a  LEFT OUTER JOIN (SELECT parent_id, COUNT(*) AS Count FROM `category` GROUP BY parent_id) Deriv1 ON a.cat_id = Deriv1.parent_id WHERE a.parent_id=" . $parent);
    echo "<nav><ul class='nav'>";
    while ($row = mysqli_fetch_assoc($result)) {
        if ($row['Count'] > 0) {
            echo "<li><a href='" . $row['category_link'] . "'>" . $row['product'] . "</a>";
            display_children($row['cat_id'], $level + 1);
            echo "</li>";
        } elseif ($row['Count']==0) {
            echo "<li><a href='" . $row['category_link'] . "'>" . $row['product'] . "</a></li>";
        } else;
    }
    echo "</ul><nav>";
}
echo display_children(0, 1);
?>

Answer 1

你的if语句不正确。使用此函数计算行数。 $ count = mysqli_num_rows（$ result）; if（$ count> 0）{..............}