如何顯示所選下拉菜單中的類別之一

Question

我需要以下代碼的幫助-當用戶從第一個下拉菜單中選擇“流派”或“平台”等類別時，我試圖顯示其中一個類別。 我不知道該怎么做

<?php # browser_catalog.php 
include ('includes/session.php');

$page_title = 'Browser Games Catalog';
include ('includes/header.php');

require_once ('mysqli_connect.php'); // Connect to the db.

// Check if the form has been submitted:
if (isset($_POST['submitted'])){

    $errors = array(); // Initialize an error array.

    // Check for a game name:
    if (empty($_POST['cat1'])) {
            $errors[] = 'You forgot to enter game name.';
    } else {
            $where = mysqli_real_escape_string($dbc, trim($_POST['cat1']));
    }

    if (empty($_POST['cat2'])) {
            $errors[] = 'You forgot to enter game name.';
    } else {
            $what = mysqli_real_escape_string($dbc, trim($_POST['cat2']));
    }

    if($where == "Genre"){

        $q = "SELECT game_name AS game, 
        platform AS pf, 
        genre AS ge, 
        game_description AS gd,
        game_price AS gp, 
        game_image AS gi,
        game_headlines AS gh
        FROM game
        WHERE  genre = '$what'";
    }
    else{

        $q = "SELECT game_name AS game, 
        platform AS pf, 
        genre AS ge, 
        game_description AS gd,
        game_price AS gp, 
        game_image AS gi,
        game_headlines AS gh
        FROM game
        WHERE platform = '$what'";
    }

    $r = \mysqli_query($dbc, $q); // Run the query.

    // Count the number of returned rows:
    $num = mysqli_num_rows($r);

    if ($num > 0) { // If it ran OK, display the records.

        echo "<p>There are currently $num number of games for '$search'.</p>\n";

        // Table header.
        echo '<table align="center" cellspacing="3" cellpadding="3" width="75%">
            <tr>
            <br>    &#09;<td align="left" padding-left:5px><b>Game Name</b></td>
            <br>    &#09;<td align="left" padding-left:5px><b>Platform</b></td>
            <br>&#09;<td align="left"><b>Genre</b></td>
            <br>    &#09;<td align="left"><b>Game Description</b></td>
            <br>    &#09;<td align="left"><b>Game Price</b></td>
            <br>    &#09;<td align="left"><b>Game Image</b></td>
            <br>    &#09;<td align="left"><b>Game Headlines</b></td>
            </tr>';

        // Fetch and print all the records:
        //<td align="left">' . "<img src = images/web/" . $row['gi']  "/>".  '</td>
        while ($row = mysqli_fetch_array($r, MYSQLI_ASSOC)) {

            echo '<tr>

                <br>    &#09;<td align="left">' . $row['game'] . '</td>
                <br>    &#09;<td align="left">' . $row['pf'] . '</td>
                <br>    &#09;<td align="left">' . $row['ge'] . '</td>
                <br>    &#09;<td align="left">' . $row['gd'] . '</td>
                <br>    &#09;<td align="left">' . $row['gp'] . '</td>
                <br> <td align="left">' . $row['gh'] . '</td>

                </tr>'; 
        }       

        echo '</table>'; // Close the table.
        mysqli_free_result ($r); // Free up the resources.  

    } else { // If no records were returned.

        echo '<p class="error">There are currently no registered users.</p>';

    }

    mysqli_close($dbc); // Close the database connection.
}
?>

<div class="page-header">

    <h1 style="font-size:40px"><center></center></h1>
</div>
<form class="form-signin" role="form" action="browser_catalog.php" method="post">


    <?php
    <p>Choose a Category:   
        <select class="form-control" id="element_6" name="category"  value="<?php if (isset($_POST['cat1'])) echo $_POST['cat1']; ?>" /> 
                <option>Platform</option>
                <option>Genre</option>
        </select>
    </p>

    if($cat1 == "Platform"){        
        <p>Platform:    
            <select class="form-control" id="element_6" name="platform"  value="<?php if (isset($_POST['cat2'])) echo $_POST['cat2']; ?>" /> 
                    <option >PC</option>
                    <option >PS4</option>
                    <option >Xbox One</option>
                    <option >Wii U</option>
                    <option >PS3</option>
                    <option >Xbox 360</option>
                    <option >Wii</option>
                    <option >Mac</option>
                    <option >Linux</option>
                    <option >Nintendo 3DS</option>
                    <option >DS</option>
                    <option >PS2</option>
                    <option >iPhone</option>
                    <option >Android</option>
            </select>
        </p>
    }
    else{
        <p>Genre:   
            <select class="form-control" id="element_6" name="genre"  value="<?php if (isset($_POST['cat2'])) echo $_POST['cat2']; ?>"> 
                <option>Action</option>
                <option>Adventure</option>
                <option>Driving</option>
                <option>RPG</option>
                <option>Strategy</option>
                <option>Sport</option>
                <option>Puzzle</option>
            </select>
        </p>
    }
    ?>
    <button style="display:inline; padding:10px; margin-bottom:5px" type="submit" name="submit" class="btn btn-sm btn-primary" />Search Game</button>
    <input type="hidden" name="submitted" value="TRUE" /></p></center>

</form>

<?php
include ('includes/footer.html');
?>

Answer 1

首先你有錯字

<p>Choose a Category:   
        <select class="form-control" id="element_6" name="category"  value="<?php if (isset($_POST['cat1'])) echo $_POST['cat1']; ?>" /> 
                <option value=>Platform</option>
                <option >Genre</option>
        </select>
    </p>

這里：

<option value=>Platform</option>

然后您在編寫php時沒有打開php標簽。 這里的例子

if($cat1 == "Platform"){      

在此之前，以及在html結束之后，您應該打開像這樣的php標簽

<?php
if($cat1 == "Platform"){   

同樣在很多地方，您混合使用html和php

同樣在這里混合html和php。 沒有打開和關閉php標簽

    </p>
    }
    else{
        <p>Genre:

我也建議您使用<input type='submit'>而不是<button type='submit'>表單。

無論如何，最好編輯您的問題並在代碼上修復語法，然后我們可以專注於您的問題，您將需要更加精確地了解代碼真正存在的問題。 謝謝編輯：這是一個例子

// not here remove this line ->    <?php
<p>Choose a Category:   
    <select class="form-control" id="element_6" name="category"  value="<?php if (isset($_POST['cat1'])) echo $_POST['cat1']; ?>" /> 
            <option>Platform</option>
            <option>Genre</option>
    </select>
</p>
// But instead here put  <?php
if($cat1 == "Platform"){ 
// And here close it ->   ?>  

休息吧，您必須為自己做些事情，因為我無法為您編寫完整的代碼，並且也有助於您學習自己的錯誤，如果可以，我可以在這里提供幫助。 閱讀w3學校網站，在那里您可以找到如何正確編寫php和html的基礎知識