服务器发出未定义的变量错误？

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我正在做一个应用程序来存储学生记录并编辑和删除它们，但服务器发出未定义的变量错误（在$ name，$ school_name，$ roll_no，$ result变量行中），尽管变量已被定义并且我已经使用过回声检查和所有的变量似乎做工精细......好心帮我服务器发出未定义的变量错误？

<form action = 'edit.php?edit_form=<?php echo $edit_id; ?>' method = 'post'> 
     <table align = "center" width = "500" border = "5"> 
      <tr> 
       <td colspan = "5"> <h1 align = "center">Update Record</h1> </td> 
      </tr> 
      <tr> 
       <td align = "right">Student Name:</td> 
       <td> <input type = "text" name = "name" value = "<?php echo $name; ?>"> </td> 
      </tr> 
      <tr> 
       <td align = "right">School Name:</td> 
       <td> <input type = "text" name = "school" value = "<?php echo $school_name; ?>"> </td> 
      </tr> 
      <tr> 
       <td align = "right">Roll No:</td> 
       <td> <input type = "text" name = "roll_no" value = "<?php echo $roll_no; ?>"> </td> 
      </tr> 
      <tr> 
       <td align = "right">Result:</td> 
       <td> <input type = "text" name = "result" value = "<?php echo $result; ?>"> </td> 
      </tr> 
      <tr> 
       <td colspan = "5" align = "center"> <input type = "submit" name = "update" value = "Update Now"> </td> 
      </tr> 
     </table> 

    </form>

来源

2016-07-26 Kamran

*什么*变量未定义？你收到的确切消息是什么？ – tadman

他们在哪里定义？ – Vuldo

你能否给我们提供填充变量的代码段？ – pilec

这实际上是有道理的，因为你是尝试设置变量呈现形式，这是在提交前，所以没有POST请求中的数据。

FOW制定工作上的事情，你必须选择从该数据库的数据，是这样的：

// mysql_connect is deprecated, use mysqli_connect instead 
$link = mysqli_connect("localhost", "root", "password"); 
mysqli_select_db($link, "school"); 

if (!isset($_GET['edit_form']) || !is_numeric($_GET['edit_form'])) { 
    // first validate user input from GET request 
    die('please provide us valid student id'); 
} 

// after successful updating showing confirmation message 
if (isset($_GET['show_message'])) { 
    echo "Data has been updated"; 
} 

$edit_id = $_GET['edit_form']; 

//using prepare statement for avoiding SQL injection 
$statement = $link->prepare('SELECT student_name, school_name, roll_no, result FROM students WHERE id = ?'); 


// i because student id should be integer 
$statement->bind_param('i', $edit_id); 

$statement->execute(); 
$statement->store_result(); 

// fill every needy variable from query 
$statement->bind_result($name, $school_name, $roll_no, $result); 
$statement->fetch(); 

if (isset($_POST['update'])) { 
    $name = $_POST['name']; 
    $school_name = $_POST['school']; 
    $roll_no = $_POST['roll_no']; 
    $result = $_POST['result']; 
    $query = "update students set student_name = ?, school_name = ?, roll_no = ?, result = ? where ID=?"; 

    // once again preparate query for avoiding SQL injection 
    $statement = $link->prepare($query); 

    // s for string variable, ssisi - 1st variable is string, 2nd variable is string, 3rd variable is integer ... 
    $statement->bind_param('ssisi', $name, $school_name, $roll_no, $result, $edit_id); 

    if ($statement->execute()) { 
     header("location: index.php?edit_form=$edit_id&show_message=1"); 
    } 
} ?>

来源

2016-07-26 07:44:45 pilec

服务器发出未定义的变量错误？

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