向通过 php/html 脚本生成的按钮添加功能答案

【问题标题】：Adding functionality to buttons generated via a php/html script向通过 php/html 脚本生成的按钮添加功能
【发布时间】：2019-02-27 06:44:44
【问题描述】：

我对 PHP/HTML/CSS 编程非常陌生，在下面附上的代码中，我尝试为网站创建管理面板的基本功能。

我想要做的是打印出包含所有行和列的表格，并添加一个带有控件的附加列，允许我从数据库中删除所述行。最终，我希望能够更改每个用户的名称、密码和管理员权限。

此外，我真的不知道如何让每个按钮保存一个将其连接到相应行的值。

也许由于我是一个非常缺乏经验的程序员，我的所有尝试要么失败，要么删除了最后一行（也许是$email 变量名下的最后一个值）。一位朋友建议使用 JavaScript 或迁移到不同的平台（Angular JS 是他的建议）以实现我的目标，但现在我真的很想用 PHP 保持简单（如果这真的是这个词的话）和 CSS。

这是管理面板的外观图片：

这是我的表格生成器（或尽我所能获得）：

<?php
    include "connection.php"; 

    $sql = "SELECT * FROM users;";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) 
    {
        echo "<table class='sqltable'>
                <tr class='sqltable'>
                    <th class='sqltable'>ID</th>
                    <th class='sqltable'>EMAIL</th>
                    <th class='sqltable'>NAME</th>
                    <th class='sqltable'>IS ADMIN</th>
                    <th class='sqltable'>PASSWORD</th>
                    <th class='sqltable'>CONTROLS</th>
                </tr>";

        // output data of each row
        while($row = $result->fetch_assoc()) 
        {
            echo "<tr class='sqltable'>                            
                    <td class='sqlcell'>".$row["ID"]."</td>
                    <td class='sqlcell'>".$row["EMAIL"]."</td>
                    <td class='sqlcell'>".$row["FIRST_NAME"]." ".$row["MID_NAME"]." ".$row["LAST_NAME"]."</td>
                    <td class='sqlcell'>".$row["IS_ADMIN"]."</td> 
                    <td class='sqlcell'>".$row["PASSWORD"]."</td>
                    <td class='sqlcell'>
                        <center>
                            <div style='border: 1px solid lightgray;' method='POST'>
                                <input type='hidden' name='ID' value='".$row['ID']." '/>
                                <input type='button' name='delete' value='DEL ".$row['ID']." '/>
                            </div>
                        </center>
                    </td>
                </tr>";
        } 
        echo "</table>";
    }

    else 
    {
        echo "DATABASE IS EMPTY!";
    }  

    $conn->close(); 

    if (isset($_POST['delete']))
    { //if a delete request received
        $id = $_POST['id']; //primary key of this row

        /////// Connectivity /////////
        $servername = "127.0.0.1";
        $username = "root";
        $password = ""; 
        $db = "myDB";    

        // Create connection
        $conn = new mysqli($servername, $username, $password, $db);

        //check connection
        if ($conn)
        {
            printf("Connect failed: %s\n", mysqli_connect_error());
            exit();
        }

        //compose sql statement
        $stmt = mysqli_prepare($conn, "DELETE FROM users WHERE ID=?");

        mysqli_stmt_bind_param($stmt,'i',$id); //now add the $id to the statement 'i' stands for integer

        mysqli_stmt_execute($stmt);

        mysqli_stmt_close($stmt);
        mysqli_close($conn); //connection closed
    }
?>

这就是我开始做的事情，我已经很确定我走错了路。

function delete()
            {
                $del = "DELETE FROM '".$table."' WHERE EMAIL='".$email."';";
                $conn->query($del);
            }

【问题讨论】：

标签： php html mysql sql mysqli

【解决方案1】：

现在，当我实现您在问题中发布的代码时，我已经更改了几处以使其正常工作，所有小问题，我将在 cmets 详细说明中将它们发布在这里。

<?php
    if (isset($_POST['delete'])) //first: test if any delete request, delete and then render the table 
    { //if a delete request received
        $id = $_POST['id']; //primary key of this row, where 'id' index must be case-sensitively equal to the hidden input name 'id'

        /////// Connectivity /////////
        $servername = "localhost";
        $username = "root";
        $password = "root"; 
        $db = "user_delete";    

        // Create connection (procedural style)
        $conn = mysqli_connect($servername, $username, $password, $db);

        //check connection
        if (!$conn) //if NOT connected
        {
            printf("Connect failed: %s\n", mysqli_connect_error()); //print error
            exit(); //exit the program 'in this case you wouldn't see the table either'
        }

        //compose sql statement
        $stmt = mysqli_prepare($conn, "DELETE FROM users WHERE ID=?"); //notice that sql statements are NOT case sensitive

        mysqli_stmt_bind_param($stmt,'i',$id); //now add the $id to the statement 'i' stands for integer

        mysqli_stmt_execute($stmt);

        mysqli_stmt_close($stmt);
        mysqli_close($conn); //connection closed, row deleted
    }

    include "connection.php"; 

    $sql = "SELECT * FROM users;";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) 
    {
        echo "<table class='sqltable'>
                <tr class='sqltable'>
                    <th class='sqltable'>ID</th>
                    <th class='sqltable'>EMAIL</th>
                    <th class='sqltable'>NAME</th>
                    <th class='sqltable'>IS ADMIN</th>
                    <th class='sqltable'>PASSWORD</th>
                    <th class='sqltable'>CONTROLS</th>
                </tr>";

        // output data of each row
        while($row = $result->fetch_assoc()) 
        {
            echo "<tr class='sqltable'>";
            echo   "<td class='sqlcell'>".$row["id"]."</td>";   //php is case-sensitive so you should use $row['ID'] according to your scheme
            echo   "<td class='sqlcell'>".$row["email"]."</td>";//php is case-sensitive so you should use $row['EMAIL'] according to your scheme
            echo   "<td class='sqlcell'>".$row["name"]."</td>";//for simplicity, I made one field, change it according to your scheme
            echo   "<td class='sqlcell'>".$row["is_Admin"]."</td>";//php is case-sensitive so you should use $row['IS_ADMIN'] according to your scheme
            echo   "<td class='sqlcell'>".$row["password"]."</td>";//same as above
            echo    "<td class='sqlcell'>
                        <center>
                            <div style='border: 1px solid lightgray;'>";
                    echo    "<form method='POST'>"; //must be added in a form with method=post
                    echo        "<input type='hidden' name='id' value='".$row['id']." '/>"; //differntiate between input name `id` and mysql field name you have `ID`, input field name is the index you will fetch in line 4: $_POST['id']
                    echo        "<input type='submit' name='delete' value='DEL ".$row['id']." '/>"; //type: submit, not button
                    echo    "</form>
                            </div>
                        </center>
                    </td>
                </tr>";
        } 
        echo "</table>";
    }

    else 
    {
        echo "DATABASE IS EMPTY!";
    }  
//all done
    $conn->close(); 
?>

更新：现在这是相同的代码，都是 OOP 风格和重用连接：

<?php
    include "connection.php"; 
    if (isset($_POST['delete'])) //first: test if any delete request, delete and then render the table 
    { //if a delete request received
        $id = $_POST['id']; //primary key of this row, where 'id' index must be case-sensitivly equal to the hidden input name 'id'

        //check connection
        if (mysqli_connect_errno()) //if connection error existed
        {
            printf("Connect failed: %s\n", mysqli_connect_error()); //print error
            exit(); //exit the program 'in this case you wouldn't see the table either'
        }

        //compose sql statement
        $stmt = $conn->prepare("DELETE FROM users WHERE ID=?"); //notice that sql statements are NOT case sensitive

        $stmt->bind_param('i',$id); //now add the $id to the statement 'i' stands for integer

        $stmt->execute();

        $stmt->close();
    }

    $sql = "SELECT * FROM users;";
    $result = $conn->query($sql);

    if ($result->num_rows > 0) 
    {
        echo "<table class='sqltable'>
                <tr class='sqltable'>
                    <th class='sqltable'>ID</th>
                    <th class='sqltable'>EMAIL</th>
                    <th class='sqltable'>NAME</th>
                    <th class='sqltable'>IS ADMIN</th>
                    <th class='sqltable'>PASSWORD</th>
                    <th class='sqltable'>CONTROLS</th>
                </tr>";

        // output data of each row
        while($row = $result->fetch_assoc()) 
        {
            echo "<tr class='sqltable'>";
            echo   "<td class='sqlcell'>".$row["id"]."</td>";   //php is case-sensitive so you should use $row['ID'] according to your scheme
            echo   "<td class='sqlcell'>".$row["email"]."</td>";//php is case-sensitive so you should use $row['EMAIL'] according to your scheme
            echo   "<td class='sqlcell'>".$row["name"]."</td>";//for simplicity, I made one field, change it according to your scheme
            echo   "<td class='sqlcell'>".$row["is_Admin"]."</td>";//php is case-sensitive so you should use $row['IS_ADMIN'] according to your scheme
            echo   "<td class='sqlcell'>".$row["password"]."</td>";//same as above
            echo    "<td class='sqlcell'>
                        <center>
                            <div style='border: 1px solid lightgray;'>";
                    echo    "<form method='POST'>"; //must be added in a form with method=post
                    echo        "<input type='hidden' name='id' value='".$row['id']." '/>"; //differntiate between input name `id` and mysql field name you have `ID`, input field name is the index you will fetch in line 4: $_POST['id']
                    echo        "<input type='submit' name='delete' value='DEL ".$row['id']." '/>"; //type: submit, not button
                    echo    "</form>
                            </div>
                        </center>
                    </td>
                </tr>";
        } 
        echo "</table>";
    }

    else 
    {
        echo "DATABASE IS EMPTY!";
    }  
//all done
    $conn->close(); 
?>

提示：在现实世界中，切勿将密码存储为纯文本，搜索和阅读更多about hashing

【讨论】：

【解决方案2】：

嗯，首先，php 脚本是服务器端脚本，这意味着您的按钮不会触发删除功能，而是会向存在删除操作的服务器发送请求。

怎么做？只需在要显示删除按钮的表格单元格内呈现一个表单（即 html 元素），然后将方法定义为 post（阅读有关 http 请求方法的更多信息），您可以包含 id 值（或该表的主键等等）。

 <form method="post">
 <input type='submit' name='delete' />
 <input type='hidden' name="id" value="$row['id']" />
 </form>

所以这个表单告诉浏览器：每当用户点击“删除”按钮时，提交这个包含一个隐藏输入的表单，其中包含要删除的元素的 id。

现在我们转到服务器端，在文件的开头：

<?php 
if (isset($_POST['delete'])){ //if a delete request received
$id = $_POST['id']; //primary key of this row

//establish connection to mysql
$mysqli = new mysqli('localhost', 'my_user', 'my_password', 'world');

//check connection
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

//compose sql statement
$stmt = $mysqli->prepare("DELETE FROM users WHERE ID=?");

$stmt->bind_param('i',$id); //now add the $id to the statement 'i' stands for integer

$stmt->execute();

$stmt->close();
$mysqli->close() //connection closed
}
?>

上面的代码是用 OOP 写的，或者你可以用 Procedural 风格写它..

<?php 
if (isset($_POST['delete'])){ //if a delete request received
$id = $_POST['id']; //primary key of this row

//establish connection to mysql
$mysqli = mysqli_connect('localhost', 'my_user', 'my_password', 'world');

//check connection
if (!$mysqli) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

//compose sql statement
$stmt = mysqli_prepare($mysqli, "DELETE FROM users WHERE ID=?");

mysqli_stmt_bind_param($stmt,'i',$id); //now add the $id to the statement 'i' stands for integer

mysqli_stmt_execute($stmt);

mysqli_stmt_close($stmt);
mysqli_close($mysqli) //connection closed
}
?>

【讨论】：

对不起，这行有一个错误：$stmt->bind_param('i',$id);，'i' 参数代表整数。这是$id 数据类型。如果您要比较字符串，请改用 's'。
等一下，我应该将$stmt = $mysqli_prepare("DELETE FROM users WHERE EMAIL=?;"); 编辑为$stmt = $mysqli->prepare("DELETE FROM users WHERE EMAIL='".$id."';");？正确的？：紧张：
如果$mysqli->prepare返回false，则表示准备此SQL语句时出错。打印 $mysqli->error 以检查此错误。
顺便说一句：我已经更新了帖子，使用mysqli_prepare，而不是$mysqli_prepare。
显然mysqli_prepare() expects exactly 2 parameters, 1 given in，我应该添加什么其他参数？ $stmt?