自动递增值分配为输入，然后使用值从数据库中删除项目；

Posted 2023-02-24

【中文标题】自动递增值分配为输入，然后使用值从数据库中删除项目；

【英文标题】：Auto Incrementing value to be assigned as input then using value to delete item from database;

【发布时间】：2021-11-20 23:17:45

【问题描述】：

我是一名学习 php 几周的学生。我想做的是生成一个包含所有用户消息的表。然后我需要在每一行中都有一个复选框。当用户点击删除按钮时，带有复选框的行将从表中删除。问题是我无法弄清楚如何为 html 表的每一行分配一个单独的值以使用 PHP 定位。所以我只会删除已经选择的行。我只能删除所有行。

这是我目前得到的结果

<?php
//connect to database 
include("../partials/.connect.php");
// select rows from contacts
$query = "SELECT * FROM contacts";
 // display table headers     
echo '<form>
     <table  border="0" cellspacing="4" cellpadding="6"> 
      <tr> 
          <th class="center">ID</th> 
          <th class="center">Name</th> 
          <th class="center">Phone</th> 
          <th class="center">Email</tdclass=center> 
          <th class="center">Message</th> 
          <th class="center"> <button type="submit" name="button1">Delete Selected</button</th>
      </tr>';
// create loop to fetch all rows from DataBase
if ($result = $conn->query($query)) 
    while ($row = $result->fetch_assoc()) 
        $field1name = $row["id"];
        $field2name = $row["name"];
        $field3name = $row["phone"];
        $field4name = $row["email"];
        $field5name = $row["message"]; 
// If delete button is clicked delete user
        if(isset($_POST['button1'])) 
            $sql = "DELETE FROM contacts WHERE id=$field1name";
        
        if ($conn->query($sql) === TRUE) 
          echo "Record deleted successfully";
         else 
          echo "Error deleting record: " . $conn->error;
        
        
// display table data 
        echo '<tr> 
                  <td class="center">'.$field1name.'</td> 
                  <td class="center">'.$field2name.'</td> 
                  <td class="center">'.$field3name.'</td> 
                  <td class="center">'.$field4name.'</td> 
                  <td class="center">'.$field5name.'</td>
                  <td class="center"> <input type="checkbox" id="if_checked" name="if_checked"></td>
              </tr>
              </form>';
    
    $result->free();
 
?>
</body>
</html>

【问题讨论】：

警告：您对SQL Injections 持开放态度，应该使用参数化的prepared statements，而不是手动构建查询。它们由PDO 或mysqli 提供。永远不要相信任何形式的输入！即使您的查询仅由受信任的用户执行，you are still in risk of corrupting your data。 Escaping is not enough!

【参考方案1】：

你的代码错了，你只是删除了你所有的数据以及你的foreach运行，所以我只想说，因为你是学生，所以继续学习更多关于编程逻辑的知识

好的，对于您的问题，您必须在之前添加删除查询

$query = "SELECT * FROM contacts";

并且您的删除查询应该基于复选框值的foreach，最重要的是您的复选框名称应该是一个数组名称，因为您将发布多个具有相同名称的复选框

<input type="checkbox" class="if_checked" name="if_checked[]">

然后你可以使用这样的代码

..................
include("../partials/.connect.php");

if(isset($_POST['button1'])) 
  foreach($_POST['if_checked'] as $id) 
    ......your delete query
  


// select rows from contacts
$query = "SELECT * FROM contacts";
...................

【参考方案2】：

您可以将复选框用作一个数组，当您选择要删除的复选框时，您将在其中存储 ID，您将遍历复选框并能够删除所有选定的行。

【参考方案3】：

我能够通过将 $row['id'] 变量存储在复选框值而不是 $Field1name 中来解决这个问题。允许我指定要删除的行。

<?php
//connect to database 
include("../partials/.connect.php");


// select rows from contacts
$query = "SELECT * FROM contacts";

//if delete button is set
  if(isset($_POST['delete'])) 
     $selected = $_POST['if_checked'];
     //confirm record target
     $confirm = mysqli_query($conn, "SELECT * FROM contacts WHERE id = '$selected'") or die("Not Found");
     if(mysqli_num_rows($confirm)>0)
         //record found delete
         $delete_query = mysqli_query($conn, "DELETE from contacts where id = '$selected'")
         or die("Not Deleted");
         echo "<div><p>Record Deleted</p></div>";
      else 
         //record not DataBase
         die("Not deleted".mysqli_error());  
  
  
 // display table headers     
echo '<form method="post" action="" role="form">
     <table  border="0" cellspacing="4" cellpadding="6"> 
      <tr> 
          <th class="center">ID</th> 
          <th class="center">Name</th> 
          <th class="center">Phone</th> 
          <th class="center">Email</th> 
          <th class="center">Message</th> 
          <th class="center"><input class="center" type="submit" name="delete" value="Delete"></th>
          
      </tr>';
      
// create loop to fetch all rows from DataBase
if ($result = $conn->query($query)) 
    while ($row = $result->fetch_assoc()) 
        $field1name = $row["id"];
        $field2name = $row["name"];
        $field3name = $row["phone"];
        $field4name = $row["email"];
        $field5name = $row["message"];
// If delete button is clicked delete user
     
// display table data 
        echo '<tr> 
                  <td class="center">'.$field1name.'</td> 
                  <td class="center">'.$field2name.'</td> 
                  <td class="center">'.$field3name.'</td> 
                  <td class="center">'.$field4name.'</td> 
                  <td class="center">'.$field5name.'</td>
                  <td class="center"> 
                  <input type="checkbox" id="if_checked" name="if_checked" value="'.$row['id'].'"></td>
              </tr>
              
              </form>';

               
  
  
    $result->free();
 
?>
</body>
</html>