如何从下拉菜单PHP的值查询行 - How to query row from a value from dropdown menu PHP

How to query row from a value from dropdown menu PHP

本文关键字：查询 PHP 下拉菜单 | 更新日期: 2023-09-27

下面是我的代码。我想查询一行，并立即打印它(onchange)后，我从下拉菜单选择。请帮助。谢谢。

<?php
$conn = new mysqli('localhost', 'root', 'jared17', 'hbadb') 
or die ('Cannot connect to db');
$result = $conn->query("select * from students");
echo "<html>";
echo "<body>";
echo "<form method = POST>";
echo "<select name = 'Students' onchange=this.form.submit()>";
while ($row = $result->fetch_assoc()) {
              unset($LRN, $First, $Last);
              $LRN = $row['LRN'];
              $First = $row['First_Name'];
              $Last = $row['Last_Name']; 
              echo '<option value="'.$First.'">'.$First.' '.$Last.'</option>';}
echo "</select>";
echo "<input type='submit' name='submit' value='Show'>";
    if(isset($_POST['submit'])) {
    echo "*******I WANT TO QUERY THE ROW I SELECTED IN DROPDOWN MENU****";
    }
echo "</form>";
echo "</body>";
echo "</html>";
?>

就这么简单

if(isset($_POST['submit'])) {
    echo $_POST['Students'];
    }

编辑:

最好使用filter_input()函数，而不是直接访问全局数组。在本例中是

$submit = filter_input(INPUT_POST,'submit');
$students = filter_input(INPUT_POST,'Students');
if(isset($submit)) {
    echo $students;
}

示例

你可以直接这样做:

if(isset($_POST['submit'])) {
   echo $_POST['Students'];
}

或者您可以使用print_r来解决您的困惑:

print_r($result);