查询未运行，switch 语句（PHP/SQL）

Question

所以我有一个下拉列表，可以更改表单下方部分中显示的信息。 switch 语句检查选择了哪个选项，然后将要运行的正确查询分配给变量 $query。我不确定为什么查询没有运行，因为我在 cPanel 的文件管理器上使用代码编辑器。我网站的另一个页面上有一个类似的 php 代码可以完美运行，所以我更加困惑。

<section class="content">
    <h2 class="heading">
        Fetal Development Navigation
    </h2>
    <div id="navigationButtons">
        <form action="" style="display:inline;" method="GET">
            <select name="week" style="width:50%; display:inline; height:5%;">
                <option title='Select A Week' value='select'>Please select a week! </option>
                <option title='Week 1' value='one'>Week 1</option>
                <option title='Week 2' value='two'>Week 2</option>
                <option title='Week 3' value='three'>Week 3</option>
                <option title='Week 4' value='four'>Week 4</option>
                <option title='Week 5' value='five'>Week 5</option>
                <option title='Week 6' value='six'>Week 6</option>
                <option title='Week 7' value='seven'>Week 7</option>
                <option title='Week 8' value='eight'>Week 8</option>
                <option title='Week 9' value='nine'>Week 9</option>
                <option title='Week 10' value='ten'>Week 10</option>
                <option title='Week 11' value='eleven'>Week 11</option>
                <option title='Week 12' value='twelve'>Week 12</option>
                <option title='Week 13' value='thirteen'>Week 13</option>
                <option title='Week 14' value='fourteen'>Week 14</option>
                <option title='Week 15' value='fifteen'>Week 15</option>
                <option title='Week 16' value='sixteen'>Week 16</option>
                <option title='Week 17' value='seventeen'>Week 17</option>
                <option title='Week 18' value='eightteen'>Week 18</option>
                <option title='Week 19' value='nineteen'>Week 19</option>
                <option title='Week 20' value='twenty'>Week 20</option>
                <option title='Week 21' value='twenty-one'>Week 21</option>
                <option title='Week 22' value='twenty-two'>Week 22</option>
                <option title='Week 23' value='twenty-three'>Week 23</option>
                <option title='Week 24' value='twenty-four'>Week 24</option>
                <option title='Week 25' value='twenty-five'>Week 25</option>
                <option title='Week 26' value='twenty-six'>Week 26</option>
                <option title='Week 27' value='twenty-seven'>Week 27</option>
                <option title='Week 28' value='twenty-eight'>Week 28</option>
                <option title='Week 29' value='twenty-nine'>Week 29</option>
                <option title='Week 30' value='thirty'>Week 30</option>
                <option title='Week 31' value='thirty-one'>Week 31</option>
                <option title='Week 32' value='thirty-two'>Week 32</option>
                <option title='Week 33' value='thirty-three'>Week 33</option>
                <option title='Week 34' value='thirty-four'>Week 34</option>
                <option title='Week 35' value='thirty-five'>Week 35</option>
                <option title='Week 36' value='thirty-six'>Week 36</option>
                <option title='Week 37' value='thirty-seven'>Week 37</option>
                <option title='Week 38' value='thirty-eight'>Week 38</option>
                <option title='Week 39' value='thirty-nine'>Week 39</option>
                <option title='Week 40' value='forty'>Week 40</option>
            </select>
            <input type="submit" value="Go" style="width:25%; display:inline; height:5%;"/>
        </form>
    </div>
</section>
<section id="week" class="content">
    <?php
        $i = $_GET['week'];
        switch ($i) {
            case "one":
                $query = "SELECT * FROM fetaldev WHERE week = 1;";
                $week = "Week One";
                break;
            case "two":
                $query = "SELECT * FROM fetaldev WHERE week = 2;";
                $week = "Week Two";
                break;
            case "three":
                $query = "SELECT * FROM fetaldev WHERE week = 3;";
                $week = "Week Three";
                break;
                case "four":
                $query = "SELECT * FROM fetaldev WHERE week = 4;";
                $week = "Week Four";
                break;
            case "five":
                $query = "SELECT * FROM fetaldev WHERE week = 5;";
                $week = "Week Five";
                break;
        }

        /*if($i == 'one') {
        $query = "SELECT * FROM fetaldev WHERE week = 1;";
                $week = "Week One";
                echo $query . $week;
                }*/
        $run = mysqli_query($dbconn, $query);
        while ($row = mysqli_fetch_array($run)){
                $id = $row['id'];
                $tag = $row['tag'];
                $description = $row['description'];
                }
        //query isn't running

        ?>
    <?php if(isset($week)){?>
    <h2 class="heading"><?php echo $week; ?></h2>
    <h4>Size Comparisons</h4>
    <?php } else { ?>
    <h3>Please select a week from the dropdown list!</h3>
    <p>Each week will list out the size comparisons and notable milestones in the development of your baby!</p>
    <?php } ?>
    <p>
        <?php if($tag == 'size'){
            echo $description . ', ';
            }?>
    </p>
    <?php if(isset($week)){?>
    <h4>Approximate Weight and Length</h4>
    <?php } ?>
    <p><?php if($tag=='weight' || $tag =='length'){echo $description;}?></p>
</section>

如果您需要代码中的更多内容，请告诉我！提前致谢！

Answer 1

试试下面的代码，我能够完全摆脱开关，使用循环最小化你的代码以防止太多的数据重复，并且让你的代码不会在 PHP 和 HTML 之间切换太多以提高可读性。我还将您切换到准备好的语句以避免 SQL 注入。

您的问题是您设置变量，然后在数据库循环之后显示信息，您必须在循环期间显示信息以获取数据库中每一行的信息。

<section class="content">
    <h2 class="heading"> 
        Fetal Development Navigation 
    </h2>
    <div id="navigationButtons">
        <form action="" style="display:inline;" method="GET">
            <select name="week" style="width:50%; display:inline; height:5%;">
                <option title='Select A Week' value='select'>Please select a week! </option>
                <?php 
                    for ($i = 1; $i <= 40; $i++) { 
                        echo "<option title='Week {$i}' value='{$i}'>Week {$i}</option>"; 
                    } 
                    ?> 
            </select>
            <input type="submit" value="Go" style="width:25%; display:inline; height:5%;"/> 
        </form>
    </div>
</section>
<?
    if(!empty($_GET['week'])) { ?>
        <section id="week" class="content"> 
            <?php 
                $week = $_GET['week']; 

                if(!empty($week)){ 
                    echo "<h2 class='heading'>{$week}</h2>"; 
                    echo '<h4>Size Comparisons</h4>'; 
                } else { 
                    echo '<h3>Please select a week from the dropdown list!</h3>'; 
                    echo '<p>Each week will list out the size comparisons and notable milestones in the development of your baby!</p>'; 
                } 
                $stmt = $db_conn->prepare("SELECT id, tag, description FROM fetaldev WHERE week=? ORDER BY tag ASC"); 
                $stmt->bind_param('s', $week); 
                $stmt->execute(); 
                $stmt->bind_result($id, $tag, $description); 
                if(!empty($week)) { 
                    echo '<h4>Approximate Weight and Length</h4>'; 
                } 
                while ($stmt->fetch()) { 
                    echo "<p>".(($tag == "size") ? $description.', ' : $tag)."</p>"; 

                    if($tag == "weight") { 
                    echo "Weight: " . $description; 
                    } 
                    if($tag == "length") { 
                    echo "Length: " . $description; 
                    } 
                } 

                ?> 
        </section>
    <?php 
    }

如果有任何问题，请告诉我，我会更新答案以反映解决方案。

Answer 2

您的逻辑有些分歧。如果查询从未运行，则不应使用仅在查询之后定义的变量。那么你不应该运行查询，除非$_GET['week'] 设置了一个值。

我已使用以下代码修改了您的代码

1. 使用for-loop 创建您的选项，因为它们每次都是相同的（只是递增） - 您可以使用它缩短几行。
2. 使用value="1" 代替value="one" 作为您的选项。这允许您在查询中直接使用该值，这样您就不需要开关来将其转换回来。
3. 在运行查询之前或在使用查询中定义的变量之前检查 isset($_GET['week'])。
4. 将查询的输出放入循环 (while ($stmt->fetch())) 中，这样您就可以获得所有记录，而不仅仅是最后一条。
5. 安全性改进：使用有界参数的预准备语句，以防止 SQL 注入。这是因为我们现在直接在查询中使用$_GET['week']。
6. 安全改进：在回显时使用htmlspecialchars($_GET['week']) - 这至少可以防止无效的 HTML（错误），但如果恶意 HTML/JavaScript 进入您的数据库，它将防止 XSS 攻击。
7. 调试：添加error_reporting(E_ALL); ini_set('display_errors', 1); 将允许您找到任何PHP 错误，使用$stmt->error 和/或$dbconn->error 将给您任何MySQL 错误。

   注意：您不应该在实时环境中显示错误 - 应该只记录它们！在开发过程中，向浏览器显示错误是可以的。

实施这些更改后，您的代码将如下所示。

<?php
// Enabling error-reporting
error_reporting(E_ALL); 
ini_set('display_errors', 1);
?>
<section class="content">
    <h2 class="heading">
        Fetal Development Navigation
    </h2>
    <div id="navigationButtons">
        <form style="display:inline;" method="GET">
            <select name="week" style="width:50%; display:inline; height:5%;">
                <option title='Select A Week' value='select'>Please select a week! </option>
                <?php 
                for ($i = 1; $i <= 40; $i++) {
                    echo '<option title=Week '.$i.'" value="'.$i.'">Week '.$i.'</option>';
                }
                ?>
            </select>
            <input type="submit" value="Go" style="width:25%; display:inline; height:5%;"/>
        </form>
    </div>
</section>
<section id="week" class="content">
    <?php
    if (isset($_GET['week'])) {
        ?>
        <h2 class="heading"><?= htmlspecialchars($_GET['week']); ?></h2>
        <?php 
        if ($stmt = $dbconn->prepare("SELECT id, tag, description FROM fetaldev WHERE week = ?")) {
            $stmt->bind_param("s", $_GET['week']);
            if (!$stmt->execute()) // If the query failed to execute
                die("Error executing query: ".$stmt->error);
            $stmt->bind_result($id, $tag, $description);
            while ($stmt->fetch()) {
                if ($tag == 'size') {
                    ?><h4>Size Comparisons</h4>
                    <p><?= htmlspecialchars($description); ?>, </p>
                    <?php 
                }

                if ($tag == 'weight' || $tag == 'length') {
                    ?><h4>Approximate Weight and Length</h4>
                    <p><?= htmlspecialchars($description); ?></p>
                    <?php 
                }
            }
            $stmt->close();
        } else {
            die("Error preparing query: ".$dbconn->error);
        }
    } else { ?>
        <h3>Please select a week from the dropdown list!</h3>
        <p>Each week will list out the size comparisons and notable milestones in the development of your baby!</p>
        <?php 
    } ?>
</section>

参考文献

• when to use htmlspecialchars() function?
• How can I prevent SQL injection in PHP?
• How to get useful error messages in PHP?
• PHP manual on mysqli_stmt::bind_param() 和 - PHP manual on mysqli_stmt::prepare()

即使这可能无法解决所有问题，也应该是找出问题所在的开始，因为我们现在已经对您的代码实施了一些错误检查。