php - 显示 firstName 的查询仅适用于一个用户

Question

我正在开发一个网页，该网页将在我的数据库中显示用户的信息。首先，我编写了一些代码来从数据库中获取名字并对其进行回显。我最初测试的用户的每个字段(用户名、名字、姓氏、密码)都填写为 "1" .为了进一步测试，我尝试注销并尝试使用不同的帐户，名字为 "Admin" .对于此帐户和所有不是第一个帐户，我收到此错误:

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, bool given in /var/www/vhosts/s4001175-ct4009.uogs.co.uk/httpdocs/profile.php on line 19

我从查看类似线程中了解到，这可能是因为查询返回 False 而不是数组，因为它应该使我相信销毁 session 没有正常工作，但是手动删除 cookie，关闭 chrome 仍然给出相同的结果。
代码:

<?php
// Starts the session 
session_start();
// If a user is not logged in, redirect to index to login
if(!isset($_SESSION['login_user'])){
   header("Location:index.html");
}


include 'config.php';

$currentUser = ($_SESSION['login_user']);


$selectUserInfo= "SELECT FirstName FROM User WHERE Username = $currentUser";

$userInfoResult = $connection -> query($selectUserInfo);

$row = mysqli_fetch_array($userInfoResult);
$FirstName = $row['FirstName'];
$LastName = $row['LastName'];
?>

使用变量:

<?php echo "<h1>$FirstName $LastName</h1>"; ?>

按照建议，我已经实现了一个 While 循环，如下所示，并修改了 SQL 以选择我需要的所有信息，而不仅仅是名字:

<?php
// Starts the session 
session_start();
// If a user is not logged in, redirect to index to login
if(!isset($_SESSION['login_user'])){
   header("Location:index.html");
}

// Includes everything from config php to set up DB connection
include 'config.php';
// Creates var from current users username 
$currentUser = ($_SESSION['login_user']);

// Query to locate the first name using the existing login as a locator
$selectUserInfo= "SELECT * FROM User WHERE Username = $currentUser";
//Executes the query and creates a variable from it
$userInfoResult = $connection -> query($selectUserInfo);

//$row = mysqli_fetch_array($userInfoResult);

while ($row = mysqli_fetch_array($userInfoResult)) {
        $FirstName = $row['FirstName'];
        $LastName = $row['LastName'];
      }
?>

同样的错误仍然存​​在，但消失了一分钟而仍然无法正常工作。无论出于何种原因，似乎都有一些奇怪的不一致，但我得到的错误仍然是:

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, bool given in /var/www/vhosts/s4001175-ct4009.uogs.co.uk/httpdocs/profile.php on line 21

Answer 1

你可以试试这个:

<?php
session_start();
if(!isset($_SESSION['login_user'])){
   header("Location:index.html");
}
include 'config.php';
// Creates var from current users username 
$currentUser = ($_SESSION['login_user']);

$sql = "SELECT * FROM User WHERE Username = '$currentUser'";
$query = mysqli_query($connection, $sql);

    while ($row = mysqli_fetch_array($query)) {
            $FirstName = $row['FirstName'];
            $LastName = $row['LastName'];
          }
?>