Question

我试图在文本框中插入一个数值，然后在点击提交时将该值添加到表格中的值。

例如，我有一个带有名为customers的表的数据库。表客户具有名称和余额列。我想在文本框中输入一个数字，然后在单击提交按钮时，我希望它将输入的值添加到余额列中的值，并在其中进行更新。换句话说，如果数据库列余额的值为50.那么当我输入一个值时，假设为20，数据库中更新的余额将为70。

我试过这个，但我只将值增加1，因为我不知道如何将输入的文本框值输入变量。

<?php
session_start();
//if user is not logged in, do nothing
if(!isset($_SESSION['email']))
{
    exit('Not logged in.');   
}

try
{
    $dbh = new PDO("mysql:host=localhost;dbname=classicmodels","root", NULL);   
}
catch(PDOException $e)
{
    exit('Database connection failed: ' . $e->getMessage());
}
$stmt = $dbh->prepare("UPDATE customers SET balance = balance + 1 WHERE email = :email");
$stmt->bindParam(':email', $_SESSION['email']) or exit("bind param failed.");
$stmt->execute() or exit("UPDATE failed.");

更新的问题在这里开始

// loggedin.php

<?php
    //if user is not logged in, then redirect to the login page
    session_start();
    if(!isset($_SESSION['email']))
    {
       header('Location: ./main.php');
    }

    //get the balance from database for logged in user
    //connect to the database
    try
    {
        $dbh = new PDO("mysql:host=localhost;dbname=classicmodels", "root", NULL);  
    }
    catch (PDOException $e)
    {
        exit('Database Connection Failed: ' . $e->getMessage());
    }

    //retrieve the click count for the logged in user
    $stmt = $dbh->prepare("SELECT balance FROM customers WHERE email = :email");
    $stmt->bindParam(':email', $_SESSION['email']);
    $stmt->execute() or exit("SELECT failed.");

    //retrieve the firstname for logged in user
    $stmt1 = $dbh->prepare("SELECT firstName FROM customers WHERE email = :email");
    $stmt1->bindParam(':email', $_SESSION['email']);
    $stmt1->execute() or exit("SELECT failed.");

    //retrieve the lastname for logged in user
    $stmt2 = $dbh->prepare("SELECT lastName FROM customers WHERE email = :email");
    $stmt2->bindParam(':email', $_SESSION['email']);
    $stmt2->execute() or exit("SELECT failed.");

    //if there is no such user, then redirect to login page
    if($stmt->rowCount() == 0)
    {
        header('Location: ./main.php');
        exit();
    }

    //extract the balance
    $row = $stmt->fetch() or exit("fetch failed.");
    $balance = $row["balance"];

    //extract the name
    $row = $stmt1->fetch() or exit("fetch failed.");
    $first = $row["firstName"];

    //extract the name
    $row = $stmt2->fetch() or exit("fetch failed.");
    $last = $row["lastName"];
?>

<head>
<title>LAB 3 - HTML & Web Programming</title>
<style>
table {
    font-family: arial, sans-serif;
    border-collapse: collapse;
    width: 100%;
}

td, th {
    border: 1px solid #dddddd;
    text-align: left;
    padding: 8px;
}

tr:nth-child(even) {
    background-color: #dddddd;
}
</style>

</head>

<!--<h1><center>LAB 3 - HTML & Web Programming</center></h1>-->
<body>
<table>
  <tr>
    <th colspan="6"><center>Banking Example</center></th>
  </tr>
  <tr>
    <td>
        Welcome,<br> <?php print($first) ?> <?php print($last) ?>
    </td>
    <td>

        Your Balance is: $<?php print($balance) ?><br><br>
    <form action="/deposit.php" method=post>
Deposit: <input type="text" name="DepositAmount" value=""><br>
<input type="submit" value="Submit">
</form>

<form action="/withdraw.php" method=post>
Withdraw: <input type="text" name="WithdrawAmount" value=""><br>
<input type="submit" value="Submit">
</form>

<form action = "logout.php" method = "post">
        <input type = "submit" value = "Logout"/>
</form>

<button type="button" onclick="alert('Your Balance is: $<?php print($balance)?>')">Check Balance</button>
    </td>
  </tr>
</table>

</body>

<div id = "error_message"></div>

<script>
function record_click()
{
    var httpRequest = new XMLHttpRequest();
    if(!httpRequest)
    {
        alert('Browser not supported');
        return;
    }
    httpRequest.onreadystatechange = function()
    {
        if(httpRequest.readyState === XMLHttpRequest.DONE)
        {
            if(httpRequest.status === 200)
            {
                if(httpRequest.responseText.length > 0)
                {
                    document.getElementById('error_message').innerHTML = httpRequest.responseText;
                }
            }
            else 
            {
                alert('There was a problem with the request.');
                return;
            }
        }
    };
    httpRequest.open('POST', 'https://cse405-luisgeesb.c9users.io/login/deposit.php');
    httpRequest.send();
}

(function()
{
    var count = <?php print($click_count)?>;
    var counter = document.getElementById('counter');
    var button = document.getElementById('button');
    button.onclick = function()
    {
        counter.innerHTML = --count;  
        record_click();
    }
})();    
</script>

// deposit.php

<?php
    session_start();
    //if user is not logged in, do nothing
    if(!isset($_SESSION['email']))
    {
        exit('Not logged in.');   
    }

    try
    {
        $dbh = new PDO("mysql:host=localhost;dbname=classicmodels","root", NULL);   
    }
    catch(PDOException $e)
    {
        exit('Database connection failed: ' . $e->getMessage());
    }

    $stmt = $dbh->prepare("UPDATE customers SET balance = balance + :DepositAmount WHERE email = :email");
    //$stmt->bindParam(':email', $_SESSION['email']) or exit("bind param failed.");
    $stmt->bindParam(':DepositAmount', $_POST['DepositAmount']) or exit("bind param failed.");
    //$stmt->execute() or exit("UPDATE failed.");


$stmt->execute(array(':email'=> $_SESSION['email'],':DepositAmount' => $_POST['DepositAmount'])) or exit("UPDATE failed.");


?>

Answer 1

// ...
$sql = "UPDATE customers 
    SET balance = balance + :transaction 
    WHERE email = :email";

$stmt = $dbh->prepare($sql);

$stmt->execute(array( 
    ':email'=> $_SESSION['email'],  
    ':transaction' => $_POST['transaction'] 
    ))  
    or exit("UPDATE failed.");

您使用<form>

在html中制作<input type="text" name="transaction" />

使用完整的代码并且有点干净，你有：

<?php
//if user is not logged in, then redirect to the login page
session_start();

if(!isset($_SESSION['email']))
   header('Location: ./main.php');

//get the balance from database for logged in user
//connect to the database
try {
    $dbh = new PDO("mysql:host=localhost;dbname=classicmodels", "root", NULL);  
}
catch (PDOException $e) {
    exit('Database Connection Failed: ' . $e->getMessage());
}

try {
    // if we have a Deposit
    if (isset($_POST['DepositAmount'])) {
        $stmt = $dbh->prepare(
            "UPDATE customers 
            SET balance = balance + :DepositAmount 
            WHERE email = :email";
            );

        $stmt->execute(array( 
            ':email'=> $_SESSION['email'],  
            ':DepositAmount' => $_POST['DepositAmount'] 
            ));
    }
    // if we have a Withdraw
    if (isset($_POST['WithdrawAmount'])) {
        $stmt = $dbh->prepare(
            "UPDATE customers 
            SET balance = balance - :WithdrawAmount 
            WHERE email = :email";
            );

        $stmt->execute(array( 
            ':email'=> $_SESSION['email'],  
            ':WithdrawAmount' => $_POST['WithdrawAmount'] 
            ));
    }

    // anyway, we get our data back
    $stmt = $dbh->prepare(
        "SELECT balance, firstName, lastName 
        FROM customers 
        WHERE email = :email"
        );

    $stmt->execute(array(':email' => $_SESSION['email']));
    $row = $stmt->fetch();

} catch (Exception $e) { // error handle
    exit('ERROR : '. $e->getMessage());
}


//if there is no such user, then redirect to login page
if(empty($row))
{
    header('Location: ./main.php');
    exit();
}

$balance = $row["balance"];
$first = $row["firstName"];
$last = $row["lastName"];
?>

<head>
<title>LAB 3 - HTML & Web Programming</title>
<style>
table {
    font-family: arial, sans-serif;
    border-collapse: collapse;
    width: 100%;
}

td, th {
    border: 1px solid #dddddd;
    text-align: left;
    padding: 8px;
}

tr:nth-child(even) {
    background-color: #dddddd;
}
</style>

</head>

<!--<h1><center>LAB 3 - HTML & Web Programming</center></h1>-->
<body>
    <table>
      <tr>
        <th colspan="6"><center>Banking Example</center></th>
    </tr>
    <tr>
        <td>
            Welcome,<br> <?php print($first) ?> <?php print($last) ?>
        </td>
        <td>

            Your Balance is: $<?php print($balance) ?><br><br>
            <form action="" method=post>
                Deposit: <input type="text" name="DepositAmount" value=""><br>
                <input type="submit" value="Submit">
            </form>

            <form action="" method=post>
                Withdraw: <input type="text" name="WithdrawAmount" value=""><br>
                <input type="submit" value="Submit">
            </form>

            <form action = "logout.php" method = "post">
                <input type = "submit" value = "Logout"/>
            </form>

            <button type="button" onclick="alert('Your Balance is: $<?php print($balance)?>')">Check Balance</button>
        </td>
    </tr>
</table>

</body>

<div id = "error_message"></div>

<script>
function record_click()
{
    var httpRequest = new XMLHttpRequest();
    if(!httpRequest)
    {
        alert('Browser not supported');
        return;
    }
    httpRequest.onreadystatechange = function()
    {
        if(httpRequest.readyState === XMLHttpRequest.DONE)
        {
            if(httpRequest.status === 200)
            {
                if(httpRequest.responseText.length > 0)
                {
                    document.getElementById('error_message').innerHTML = httpRequest.responseText;
                }
            }
            else 
            {
                alert('There was a problem with the request.');
                return;
            }
        }
    };
    httpRequest.open('POST', 'https://cse405-luisgeesb.c9users.io/login/deposit.php');
    httpRequest.send();
}

(function()
{
    var count = <?php print($click_count)?>;
    var counter = document.getElementById('counter');
    var button = document.getElementById('button');
    button.onclick = function()
    {
        counter.innerHTML = --count;  
        record_click();
    }
})();    
</script>

Answer 2

我不是PDO的专家，我不知道这样的语法是否有效但提交表单时，检索表单的新值（$ _GET或$ _POST）并使用该值而不是声明中的数字1 ......类似......

$new_value = $_GET['new_value_from_the_form'];
$stmt = $dbh->prepare("UPDATE customers SET balance = balance + 
$new_value WHERE email = :email");

How to update field to add value to existing value?

如何从文本框中获取数值并使用该数值更新数据库？

更新的问题在这里开始

2 个答案: