对于php中的mysql查询，如何将一个表单元素值传递给下一个表单元素？_Php_Mysql

对于php中的mysql查询，如何将一个表单元素值传递给下一个表单元素？

php mysql

对于php中的mysql查询，如何将一个表单元素值传递给下一个表单元素？,php,mysql,Php,Mysql,我正在努力做到以下几点：用户选择一个座位区基于该区域，特定座位将可用数据库和表已就位且正确无误我的问题是获取用户为区域选择的值，并使用它来查询座位。代码如下： <form method="post"> <?php $sql = "select Name from Zone"; $handle = $conn->prepare($sql); $handle->execute(array()); $res = $handle->fetchAll();

我正在努力做到以下几点：

用户选择一个座位区

基于该区域，特定座位将可用

数据库和表已就位且正确无误

我的问题是获取用户为区域选择的值，并使用它来查询座位。代码如下：

<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>

这真的让我很沮丧，任何有助于取得突破的有用提示都会非常有用。提前谢谢

[编辑：由于这是一项评估，我选择将表格分解为各个组成部分，并将提交时的数据从一个元素传递到下一个元素。即：

选择区域->提交-> 使用所选区域查询数据库中的相对座位，并填充下一个下拉列表

我已经用这种方法工作了。它很粗糙，但能完成工作，这是我自己的想法（这是一个评估）

然而，Craig和RamRaider为其他面临这一挑战的人提供了更加优雅的解决方案。]

解决这类问题的最佳方法（IMO）是使用

Ajax

使用某种脚本或其他脚本（在这种情况下，相同的页面可能是完全不同的脚本）从数据库请求数据

HTML页面上的初始下拉菜单将有一个事件侦听器（

onchange

），当用户从菜单中选择时，它将触发ajax请求。以下内容未经测试，但可能会给出一个想法

<?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>

考虑这个使用HTML、PHP、MySQL和一个平面Javascript命令的工作示例：

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;

<?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;
  }
}

Hello and welcome to SO:）我曾经对如何完成类似的事情做了一次很好的解释，这可能会对您有所帮助：但是看看您的用例，您似乎需要一些Javascript来检测select何时更改，并基于此提交表单？下面是一个例子：要学习的内容很多，从PHP网页脚本的生命周期开始，这也是错误的$sql=“选择行数，从座位开始的区域，其中区域=”.$Zone
作为文本值，需要像下面这样用引号括起来$sql=“select RowNumber，Zone from Seat WHERE Zone=”$Zone'你知道你错过了选项的值属性，是吗？因此，不会为任何选择的选项提交任何内容。是的，但是，唉，我不被允许，我只能使用JS、PHP和mySQL，因为这是我正在评估的。呃。。。ajax是javascriptWell，它与xml的关系越来越密切。我们已经被告知不能使用它。必须坚持纯JS。刚刚看到编辑。谢谢你，伙计。明天我会详细复习，看看能学到什么。但是有一件事是肯定的，我不能容易受到注入攻击，或者我会失去分数。为了避免sql注入（f）检查，请使用准备好的语句，并且作为额外的预防措施，对用户输入进行清理。非常感谢您花时间这么做。我明天将进行取证。@ScheurichGolzari供您参考，对代码进行了一些修改，以解决一些逻辑问题，我仍然看到一些问题，但认为它提供了一个很好的示例，说明您可能如何处理问题。
<?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;
  }
}