从数据库变量php填充下拉列表

Question

我试图用数据库中的变量填充下拉列表，但下拉列表显示为空。我认为问题在于我是如何回显数据的。

<div class="col sm-4">
    <label for="paperSelects1"><b>Select Breed to Update</b></label>

    <select id='updatebreed' name='ubreed'>

            <?php while($row = $result->fetch_assoc() ){
                $breed_data = $row['breed'];
                $dogid = $row['dogid'];
            
                echo "<option value='$dogid'> $row </option>";
            }
            ?>
            
    </select> 
        <input type="submit" value="Submit">
</div>

这是我与数据库的连接。我哪里错了？

<?php

    include("../config/connect.php");

    $read = "SELECT * FROM dog_best_in_show ";
   
    $result = $conn->query($read);

?>

Answer 1

您使用了错误的php变量，该变量未赋值，请更新，因此请更新它

 echo "<option value='$dogid'> $row </option>";

至

 echo "<option value='$dogid'> $breed_data</option>";

你的完整代码是这样的，我使用pdo连接，所以这是pdo代码

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test";
?>


<div class="col sm-4">
<label for="paperSelects1"><b>Select Breed to Update</b></label>

<select id='updatebreed' name='ubreed'>
    <?php
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $stmt = $conn->prepare("SELECT * FROM dog_best_in_show");
    $stmt->execute();
    // set the resulting array to associative
    $result = $stmt->fetchAll();
    foreach ($result as $k => $v) {

        $breed_data = $v['breed'];
        $dogid = $v['dogid'];

        echo "<option value='$dogid'> $dogid </option>";
    }
    ?>

</select>
<input type="submit" value="Submit">
</div>

Answer 2

怎么样

echo "<option value='$dogid'>$breed_data</option>";

而不是

echo "<option value='$dogid'> $row </option>";

此外，您应该始终交叉检查您的输出与浏览器的开发工具(Chrome，Firefox)。