MySql-PDO更新记录的一部分

Question

我正在尝试学习MySql / PDO并且已经按照教程展示了如何设置crud。它工作正常。但是，我希望能够更新记录中的3个字段，但似乎无法使其正常工作。我是否需要在小更新字符串中使用完整结构，或者只需要我想要更新的字段。 这是适用于完整数据库结构的代码： -

        // update data
        if ($valid) {
            $pdo = Database::connect();
            $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

            $sql = "UPDATE customers  set outstanding = ?, estimate = ?, fault_Description = ?, item_Description = ?, email = ?, mobile = ?, name = ?, address = ?, address2 = ?, town = ?, county = ?, postcode = ?, condition01 = ?, leads = ?, model = ?, username = ?, password = ?, backed_Up = ?, location = ? WHERE id = ?";

            $q = $pdo->prepare($sql);
/*            $q->execute(array($coa,$version,$activated,$owner,$notes,$id));  */
            $q->execute(array($outstanding,$estimate,$fault_Description,$item_Description,$email,$mobile,$name,$address,$address2,$town,$county,$postcode,$condition01,$leads,$model,$username,$password,$backed_Up,$location,$id));
            Database::disconnect();
            header("Location: test-index.php");
        }
    } else {
        $pdo = Database::connect();
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
/*        $sql = "SELECT * FROM serials where id = ?";  */
        $sql = "SELECT * FROM customers where id = ?";
        $q = $pdo->prepare($sql);
        $q->execute(array($id));
        $data = $q->fetch(PDO::FETCH_ASSOC);
        $outstanding = $data['outstanding'];
        $estimate = $data['estimate'];
        $fault_Description = $data['fault_Description'];
        $item_Description = $data['item_Description'];
        $email = $data['email'];
        $mobile = $data['mobile'];
        $name = $data['name'];
        $address = $data['address'];
        $address2 = $data['address2'];
        $town = $data['town'];
        $county = $data['county'];
        $postcode = $data['postcode'];
        $condition01 = $data['condition01'];
        $leads = $data['leads'];
        $COA = $data['COA'];
        $model = $data['model'];
        $username = $data['username'];
        $password = $data['password'];
        $backed_Up = $data['backed_Up'];
        $location = $data['location'];
        Database::disconnect();
    }
?>

我想要更新的唯一字段是Outstanding Estimate and Location。

更新： 根据评论我已经减少了对此的完整工作更新，但它不起作用： -

<?php
    require 'test-database.php';

    $id = null;
    if ( !empty($_GET['id'])) {
        $id = $_REQUEST['id'];
    }

    if ( null==$id ) {
        header("Location: test-workshop.php");
    }

    if ( !empty($_POST)) {
        // keep track validation errors
        $fault_DescriptionError = null;

        // keep track post values
        $fault_Description = $_POST['fault_Description'];

        // validate input
        if (empty($fault_Description)) {
            $nameError = 'Please Describe the fault';
            $valid = false;
        }
        // update data
        if ($valid) {
            $pdo = Database::connect();
            $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            $sql = "UPDATE customers
            set fault_Description = ?
            WHERE id = ?";

            $q = $pdo->prepare($sql);
            $q->execute(array($fault_Description,$id));
            Database::disconnect();
            header("Location: test-workshop.php");
        }
    } else {
        $pdo = Database::connect();
        $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $sql = "SELECT fault_Description
        FROM customers
        where id = ?";
        $q = $pdo->prepare($sql);
        $q->execute(array($id));
        $data = $q->fetch(PDO::FETCH_ASSOC);
        $fault_Description = $data['fault_Description'];
        Database::disconnect();
    }
?>
<div class="container">
<div class="span10 offset1">
   <div class="row">
   <h3>Update a Customer</h3>
   </div>
<form class="form-horizontal" action="update-yyy.php?id=<?php echo $id?>" method="post">
   <div class="control-group <?php echo !empty($fault_DescriptionError)?'error':'';?>">
      <label class="control-label">Fault Description</label>
      <div class="controls">
      <input name="fault_Description" type="text" placeholder="fault_Description" value="<?php echo !empty($fault_Description)?$fault_Description:'';?>">
      <?php if (!empty($fault_DescriptionError)): ?>
      <span class="help-inline"><?php echo $fault_DescriptionError;?></span>
      <?php endif;?>
      </div>
   </div>
 <div class="form-actions">
   <button type="submit" class="btn btn-success">Update</button>
   <a class="btn" href="test-workshop.php">Back</a>
 </div>
 </form>