我正在尝试执行以下操作：
数据库和表格已就位且正确无误。
我的问题是获取用户为区域选择的值并使用它来查询席位。这是代码：
<form method="post">
<?php
$sql = "select Name from Zone";
$handle = $conn->prepare($sql);
$handle->execute(array());
$res = $handle->fetchAll();
echo "<select name='Zone'>";
foreach($res as $row) {
echo "<option>".$row['Name']."</option>";
}
echo "</select>";
?>
<?php
$zone = $_POST['Zone'];
$sql = "select RowNumber, Zone from Seat WHERE Zone =" .$zone;
$handle = $conn->prepare($sql);
$handle->execute(array());
$conn = null;
$res = $handle->fetchAll();
echo "<select name='Seat'>";
foreach($res as $row) {
echo "<option>".$row['RowNumber']."</option>";
}
echo "</select>";
?>
</form>
这真让我感到沮丧，任何有用的技巧都会有所帮助。提前谢谢。
[编辑： 由于这是一项评估，我选择将表格分解为其组成部分，并将提交数据从一个元素传递到下一个元素。那就是：
选择区域 - ＆gt;提交 - ＆gt; 使用选定的区域查询数据库中的相对席位，然后填充下一个下拉列表。
我有这个方法可以工作。它是粗糙的，但它完成了工作和我自己的想法（这是一个评估）。
然而，Craig和RamRaider为遇到这一挑战的其他人提供了更优雅的解决方案。]答案 0 :(得分：1)
此类问题的最佳方法（IMO）是使用Ajax使用某些脚本或其他脚本（在这种情况下是同一页面但可能是完全不同的脚本）从数据库请求数据< / p>
HTML页面上的初始下拉菜单将有一个事件监听器（onchange），当用户从菜单中选择时，它将触发ajax请求。以下未经过测试，但也许应该提出一个想法。
<?php
/*
db & other includes etc
*/
/*
Ajax POST request is processed here
*/
if( $_SERVER['REQUEST_METHOD']=='POST' && !empty( $_POST['zone'] ) ){
/* clean output buffers to ensure no unexpected data is in the response */
ob_clean();
/* Write data/response to an array */
$response=array();
/* !! By directly embedding variables in the sql you open your code to SQL injection!! */
$sql = "select `RowNumber`, `Zone` from `Seat` WHERE `Zone` ='" . $_POST['zone'] ."';";
$handle = $conn->prepare( $sql );
$handle->execute();
$conn = null;
$res = $handle->fetchAll();
/* Process the recordset: add an option for each row found */
foreach( $res as $row ) {
$response[]="<option>".$row['RowNumber'];
}
/* Send the response data to the ajax callback function */
exit( implode( PHP_EOL, $response ) );
}
?>
<!doctype html>
<html>
<head>
<title>Ajax menu</title>
<script type='text/javascript' charset='utf-8'>
/* Simple ajax function to send request to same page and fetch new data from db */
function fetchrows( name ){
var xhr=new XMLHttpRequest();
xhr.onreadystatechange=function(){
if( xhr.readyState==4 && xhr.status==200 ) plotrows.call( this, xhr.response );
};
xhr.open( 'POST', location.href, true );
xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
xhr.send( 'zone='+value );
}
/* ajax callback */
function plotrows( response ){
document.getElementById('seat').innerHTML=response;
}
</script>
</head>
<body>
<form method="post">
<?php
/*
Initial dropdown menu with an `onchange` event handler that triggers
an ajax request to the same script but calls a sql command to generate
the menu contents for the second menu.
*/
$sql = "select `name` from `zone`";
$handle = $conn->prepare( $sql );
$handle->execute();
$res = $handle->fetchAll();
echo "<select name='Zone' onchange='fetchrows( this.value )'>";
foreach( $res as $row ) {
echo "<option>".$row['Name'];
}
echo "</select>";
?>
<!-- This will be populated by javascript with appropriate options -->
<select name='seat' id='seat'></select>
<!--
More form content and further HTML....
-->
</form>
</body>
</html>
要在没有AJAX的情况下获得相同的最终结果（或多或少），您可以使用javascript函数将zone附加到查询字符串并在构造sql时使用它。
<!doctype html>
<html>
<head>
<title>Not ajax menu</title>
<script type='text/javascript' charset='utf-8'>
function fetchrows( name ){
location.search='zone='+name
}
</script>
</head>
<body>
<form method="post">
<?php
$sql = "select `name` from `zone`";
$handle = $conn->prepare( $sql );
$handle->execute();
$res = $handle->fetchAll();
echo "<select name='Zone' onchange='fetchrows( this.value )'>";
foreach( $res as $row ) {
echo "<option>".$row['Name'];
}
echo "</select>";
?>
<select name='seat'>
<?php
if( $_SERVER['REQUEST_METHOD']=='GET' && !empty( $_GET['zone'] ) ){
/* !! By directly embedding variables in the sql you open your code to SQL injection!! */
$sql = "select `RowNumber`, `Zone` from `Seat` WHERE `Zone` ='" . $_GET['zone'] ."';";
$handle = $conn->prepare( $sql );
$handle->execute();
$conn = null;
$res = $handle->fetchAll();
foreach( $res as $row ) {
echo="<option>".$row['RowNumber'];
}
}
?>
</select>
<!--
More form content and further HTML....
-->
</form>
</body>
</html>
答案 1 :(得分：1)
考虑这个使用HTML，PHP，MySQL和一个平面Javascript命令的工作示例：
<强>的index.php
<?php
// Include the class that handles the database interactivity
require_once 'Database.php';
// Initialise the database
$Database = new Database();
// Get the list of Zones
$Zones = $Database->getZones();
// ZONE
if (isset($_POST['Zone'])) {
// You could validate and whitelist entries here if you wanted
if (!in_array($_POST['Zone'], $Zones)) {
$response = 'Sorry but that was not a valid selection';
}
// Passed validation
else {
// Get the corresponding Seats
$Seats = $Database->getSeats($_POST['Zone']);
// Store the Zone selection
$selectedZone = $_POST['Zone'];
// Set the response
$response = 'Viewing seats for '.$_POST['Zone'];
}
}
// SEAT
if (isset($_POST['Seat'])) {
printf('Zone that was chosen: '.$selectedZone);
printf('<br>');
printf('Seat that was chosen: '.$_POST['Seat']);
exit;
}
// This deals with initally loading the page
if (!isset($_POST['Zone']) && !isset($_POST['Seat'])) {
// Open variables
$response = '';
$selectedZone = 'n/a';
$Seats = array();
}
// You could move the code from here onwards into another file
// So you have a template like:
// require_once 'view.php'; which has a form that posts to index.php
// Start generating the page html
$page = '
<!DOCTYPE html>
<html>
<head>
<title>Awesome Page!</title>
</head>
<body>
<form method="POST" action="index.php">
';
// If theres a response to display
if (strlen($response) > 0) {
$page .= '
<p>'.$response.'</p>
';
}
// Dealing with the Zone selection
$page .= '
<p>Zones</p>
<select name="Zone" onchange="this.form.submit()">
<option value="">Please select an option</option>
';
// Itterate over the Zones
foreach ($Zones as $name) {
// If this is the selected Zone
if ($selectedZone == $name) {
$page .= '
<option selected value="'.$name.'">'.$name.'</option>
';
}
// This is not a selected Zone
else {
$page .= '
<option value="'.$name.'">'.$name.'</option>
';
}
}
$page .= '
</select>
';
// Dealing with the Seat selection
if (count($Seats) > 0) {
$page .= '
<p>Seats</p>
<select name="Seat" onchange="this.form.submit()">
<option value="">Please select an option</option>
';
// Itterate over the Seats
foreach ($Seats as $RowNumber) {
$page .= '
<option value="'.$RowNumber.'">Row Number: '.$RowNumber.'</option>
';
}
$page .= '
</select>
';
}
// Theres no Seats yet as Zone is not selected
else {
$page .= '
<p>Please select a Zone first.</p>
';
}
$page .= '
</form>
</body>
</html>
';
// Display the page
echo $page;
<强> database.php中
<?php
class Database
{
// Active connection
private $link;
// This fires when you call new Database();
public function __construct()
{
$this->doConnect();
}
private function doConnect()
{
// Define database details
$DBHost = 'localhost';
$DBUser = 'username';
$DBPass = 'password';
$DBName = 'database_name';
// Create a database connection for PHP to use
$this->link = mysqli_connect($DBHost, $DBUser, $DBPass);
// Preform from tasks to ensure the connection is active
if (!$this->link) {
echo 'Error: Unable to connect to MySQL' . '<br>';
echo 'Debugging errno: ' . mysqli_connect_errno() . '<br>';
echo 'Debugging error: ' . mysqli_connect_error() . '<br>';
exit;
}
// Sets encoding type to uft8
if (!mysqli_set_charset($this->link, 'utf8')) {
$this->processError();
}
// Set database that is in use (makes queries shorter to write)
if (!mysqli_select_db($this->link, $DBName)) {
$this->processError();
}
}
public function getZones()
{
// Stores the result
$Zones = array();
// Build query
$query = 'SELECT `name` ';
$query .= 'FROM `Zone` ';
// Prepare the statement
if (!$stmt = $this->link->prepare($query)) { $this->processError(); }
// Execute the query
if (!$stmt->execute()) { $this->processError(); }
// Bind variable to query values
if (!$stmt->bind_result($name)) { $this->processError(); }
// Itterate over the rows
while ($stmt->fetch()) {
// Add this Zones name to the result
$Zones[] = $name;
}
// Close the statement
$stmt->close();
// Return the result
return $Zones;
}
public function getSeats($selectedZone)
{
// Stores the result
$Seats = array();
// Build query
$query = 'SELECT `RowNumber` ';
$query .= 'FROM `Seat` ';
$query .= 'WHERE `Zone` = ? ';
// Prepare the statement
if (!$stmt = $this->link->prepare($query)) { $this->processError(); }
// Bind in form values to prevent sql injection
if (!$stmt->bind_param('s', $selectedZone)) { processError($link); } // NB: Assumed this to be a string but might be an integer, if so use i instead of s
// Execute the query
if (!$stmt->execute()) { $this->processError(); }
// Bind variable to query values
if (!$stmt->bind_result($RowNumber)) { $this->processError(); }
// Itterate over the rows
while ($stmt->fetch()) {
// Add this RowNumber to the Seats
$Seats[] = $RowNumber;
}
// Close the statement
$stmt->close();
// Return the result
return $Seats;
}
private function processError()
{
echo 'Error: Unable to connect to MySQL' . '<br>';
echo 'Debugging errno: ' . $this->link->errno . '<br>';
echo 'Debugging error: ' . $this->link->error . '<br>';
exit;
}
}
基本上，我们的PHP位在顶部处理获取数据和表单提交，然后我们在其下面有html模板，其中包含一个提交给自己的表单。
模板（逻辑视图类型）将利用由Database类（模型逻辑类型）辅助的第一位（控制器类型的逻辑）提供的数据。
因此，这是一个非常简单的MVC模式实现。
Javascript的使用非常简单，以便检测选择值的变化，然后提交表单：onchange="this.form.submit()"
我尽可能地对代码进行评论，以便增加对您的理解，但如果您有任何疑问，请随时询问：）