PHP中的isset（）不起作用

Question

我可以知道為什么isset塊中的回聲沒有出現嗎？ 是因為我在php中回顯html代碼的方式嗎？ 任何解釋將不勝感激。

下面是我的代碼：

<?php

    while($row = mysqli_fetch_array($result))
    {
        echo "<tr>";
        echo "<td>" . $row[1] . "</td>";
        echo "<td>" . $row[2] . "</td>";
        echo "<td>" . $row[3] . "</td>";
        echo "<td>" . $row[4] . "</td>";
        echo "<td>" . $row[5] . "</td>";
        echo "<td>" . $row[6] . "</td>";
        echo "<td>" . $row[7] . "</td>";
        echo "<td>
              <ul class=\"form-style-1\">
                <select name=\"option_update\" class=\"field-select\">
                    <option value=\"approved\">Approve</option>
                    <option value=\"declined\">Decline</option>
                    <option value=\"pending\">Pending</option>
                </select>
                <input type=\"submit\" value=\"update\" name=\"update_value\"/>
              </ul>
            </td>";
        echo "</tr>";

    }
?>
</table>
<?php

    if(isset($_POST['update_value'])){

        echo "test";
    }

?>

Answer 1

嘗試這個：

    while($row = mysqli_fetch_array($result))
    {
        echo "<tr>";
        echo "<td>" . $row[1] . "</td>";
        echo "<td>" . $row[2] . "</td>";
        echo "<td>" . $row[3] . "</td>";
        echo "<td>" . $row[4] . "</td>";
        echo "<td>" . $row[5] . "</td>";
        echo "<td>" . $row[6] . "</td>";
        echo "<td>" . $row[7] . "</td>";
        echo "<td>
            <form action="#" method="post"> 
              <ul class=\"form-style-1\">
                <select name=\"option_update\" class=\"field-select\">
                    <option value=\"approved\">Approve</option>
                    <option value=\"declined\">Decline</option>
                    <option value=\"pending\">Pending</option>
                </select>
                <input type=\"submit\" value=\"update\" name=\"update_value\"/>
             **</form>**
              </ul>
            </td>";
        echo "</tr>";

    }
?>
</table>
<?php

    if(isset($_POST['update_value'])){

        echo "test";
    }

?>

Answer 2

要從$ _POST獲取變量，您必須從HTML表單提交它們

<form method="post"> 

https://www.w3schools.com/php/php_forms.asp