从数据库填写表格，然后用更多信息更新数据库

Question

这可能很简单，但我只是无法让最后一点工作。我有一个 PHP/HTML 表单。部分由查询数据库填写，部分由用户填写。除了 PHP 写入数据库中的最后一条 $sql 语句外，一切正常。基本上，表单页面的第二部分检索一些用户存储的信封，然后允许用户输入要放入该信封的金额。我需要存储该金额，但有很多信封，我需要确保输入的金额对应正确的信封。如您所见，我迷路了。

这是主要形式：

    <form action="newpaycheck.php" method="post">
<div id="col2top">
<?php
 include 'includes/connection.php';
    echo "<select name= 'bankaccount'>";
    echo '<option value="">'.'--- Bank Account ---'.'</option>';
    $query = mysqli_query($con,"SELECT bankaccount FROM bankaccounts");
    $query_display = mysqli_query($con,"SELECT bankaccount FROM bankaccounts");
    while($row=mysqli_fetch_array($query))
        {
        echo "<option value='". $row['bankaccount']."'>".$row['bankaccount']
        .'</option>';
        }
    echo '</select>';
?><br><br>
    Amount: <input type="text" name="paycheckamount"><br><br>
    Name: <input type="text" name="paycheckname"><br><br>
    Date: <input type="text" name="normaldate">
</div>
<div id="col2bottom">
<?php
    $result = mysqli_query($con,"SELECT envelopename, envelopebudget FROM envelopes");

    echo "<table border='1'>
    <tr>
    <th>Envelope</th>
    <th>Budget</th>
    <th>Amount</th>
    </tr>";

    while($row = mysqli_fetch_array($result)) {
    echo "<tr>";
    echo "<td>" . $row['envelopename'] . "</td>";
    echo "<td>" . $row['envelopebudget'] . "</td>";
    ?><td><input type="text" name="budgetamount"></td><?php;
    echo "</tr>";
    }

    echo "</table>";
?>  
    <input type="submit">

</div>
</form> 
</div>

这是将所有内容写入数据库的内容：

<?php
//MySQL Database Connect
 include 'includes/connection.php';

// escape variables for security
$bankaccount = mysqli_real_escape_string($con, $_POST['bankaccount']);
$paycheckamount = mysqli_real_escape_string($con, $_POST['paycheckamount']);
$paycheckname = mysqli_real_escape_string($con, $_POST['paycheckname']);
$normaldate = mysqli_real_escape_string($con, $_POST['normaldate']);
$budgetamount = mysqli_real_escape_string($con, $_POST['budgetamount']);

$sql="INSERT INTO paychecks (bankaccount, paycheckamount, paycheckname, normaldate)
VALUES ('$bankaccount','$paycheckamount','$paycheckname','$normaldate')";
if (!mysqli_query($con,$sql)) {
  die('Error: ' . mysqli_error($con));
}

$sql="ALTER TABLE envelopes ADD COLUMN $paycheckname varchar (50)";
if (!mysqli_query($con,$sql)) {
  die('Error: ' . mysqli_error($con));
}

$sql="UPDATE envelopes SET '$paycheckname'='$budgetamount' WHERE envelopename ='$envelopename'";

if (!mysqli_query($con,$sql)) {
  die('Error: ' . mysqli_error($con));
}
echo "1 record added";

mysqli_close($con);

Answer 1

不应引用列名。改变

$sql="UPDATE envelopes SET '$paycheckname'='$budgetamount' WHERE envelopename ='$envelopename'";

到

$sql="UPDATE envelopes SET $paycheckname='$budgetamount' WHERE envelopename ='$envelopename'";

如果你愿意，你可以使用反引号

$sql="UPDATE envelopes SET `$paycheckname`='$budgetamount' WHERE envelopename ='$envelopename'";