PHP/MySQL 双循环

Question

我正在处理一个目录，其中一些列表具有与其关联的图像，而其他列表则没有。我想知道如何在循环中编写循环来获取结果。

例如，用户选择他们想要结果的州，查询将转到数据库，请求该州的所有列表。

<?php
if (isset($_POST['searchButton'])) {

$state = $_POST['state'];

$query = "SELECT * FROM directory LEFT JOIN directory_images ON directory.id = directory_images.user_id WHERE directory.state = '$state' ";
$result = mysql_query($query) or die(mysql_error());

if (mysql_num_rows($result) == 0) {
    echo "<p>Sorry, there are no listings in '$state', check back soon!</p>\n";
}
else
    while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
        $id = $row['id'];
        $name = $row['name'];
        $address = $row['address'];
        $city = $row['city'];
        $state = $row['state'];
        $zip = $row['zip'];
        $has_support_pics = $row['file_name'];
        ?>

        <h4><?php echo $name ?></h4>
        <p><?php echo $address ?><br/>
            <?php echo $city . ' ' . $state . ', ' . $zip; ?><br/>
        </p>            
        <?php
        // check to see if ID has extra images
        if (isset($has_support_pics)) {
                    $query2 = "SELECT file_name FROM directory_images WHERE user_id = '$id'";
                    $result2 = mysql_query($query2) or die(mysql_error());
                    echo $query2.'<br/>';
                    ?>
                    <ul class="support_images">
                        <?php
                        while ($row = mysql_fetch_array($result2, MYSQL_ASSOC)) {
                            $support_image = $row['file_name'];
                            echo $support_image.'<br/>';
                                }
                            ?>
                    </ul>
                </div>
                <br/>
            </div>
            <?php
        }
        echo "<hr/>";
    }

}？>

Answer 1

不要在循环中运行查询 - 使用联接。这是一个教程:http://thewebmason.com/tutorial-parent-child-lists/