php - 类别和子类别

Question

我对类别和子类别有疑问。我无法获取与类别相同的category_id 中的子类别数据。我定义子类别category_id的方式与类别category_id相同，子类别父级是2。

Database is here

<?php 
//connect to Mysql database
include "storescripts/connect_to_mysql.php"; 
// This block grabs the whole list for viewing
$dynamic_menu = "";
$sql = mysql_query("SELECT * FROM `category` WHERE `parent` IS NULL ORDER BY `category`.`name` ASC");
$productCount = mysql_num_rows($sql); // count the output amount
if ($productCount > 0)
	{
	while($row = mysql_fetch_array($sql)){
			 $id = $row["id"];
			 $name = $row["name"];
			 $parent = $row["parent"];
			 $category_id = $row["category_id"];
			 $dynamic_menu .= '<div class="menu-primary">
                <li><a>'.$name.'</a></li></div>
				<div class="menu-under">
            <li><a>'.$name.'</a></li>
        </div>';

}} else {
	$dynamic_menu = "You have no products listed in our store yet";
}
?>

<div class="menu">
    <?php echo $dynamic_menu; ?>
</div>


<!--

I'd like to html created like below 

<div class="menu-primary">
        	<li><a>Kaamerad</a></li>
        </div>
        <div class="menu-under">
        	<ul>
            <li><a>optikad</a></li>
            <li><a>mälukaardid</a></li>
            </ul>
        </div>
-->

Answer 1

在 While 循环中，您必须包含另一个查询来获取特定类别的子类别(从 id 字段获取子类别后)，即父级是某个类别 ID。