没有错误，但查询没有返回任何结果

Nothing is showing, and no error is output. I have defined $id. Any ideas?

<tr>
<td width="160">Price:</td>
<?php
    dbconnect(); 
    $stmt2 = $conn->prepare("SELECT Length, price FROM Product WHERE ProdID=:id LIMIT 1");
    $stmt2->bindParam('id',$id);
    $stmt2->execute();
    $i = 0;
    foreach ($stmt2->fetchAll(PDO::FETCH_ASSOC) as $row2) {
        if ($i == 0) {  
            echo '<td>'.$row2['Price'].'</td>';
        }
    }
?>
</tr>

In you're SQL you try to select "price" (lower "p"), but you try to echo $row2['Price'] (upper "P"). Try this or change the p in "Price" to lowercase!

<tr>
    <td width="160">Price:</td>
    <?php
        dbconnect(); 
        $stmt2 = $conn->prepare("SELECT Length, Price FROM Product WHERE ProdID=:id LIMIT 1");
        $stmt2->bindParam('id',$id);
        $stmt2->execute();
        $i = 0;
        foreach ($stmt2->fetchAll(PDO::FETCH_ASSOC) as $row2) {
            if ($i == 0) {  
                echo '<td>'.$row2['Price'].'</td>';
            }
        }
    ?>
</tr>

If this is not working, try your SQL-code in PHPMyAdmin. If the data will be displayed, your SQL would be right.