mysqli不执行Select语句

I have the code bellow. When I use this code without the WHERE clause, all the users from the table are displayed, as expected. But when the WHERE clause is used, nothing is displayed.

我有下面的代码。当我在没有WHERE子句的情况下使用此代码时,将按预期显示表中的所有用户。但是当使用WHERE子句时,不会显示任何内容。

What could be the cause and how can I fix it?

可能是什么原因以及如何解决?

Thank you!

function requestUser($user) {
  $DBHost   = "localhost";
  $DBUser   = "dbUser";
  $DBPass   = "dbPass";
  $DBName   = "dbName";

  $db = new mysqli($DBHost, $DBUser, $DBPass, $DBName);
  if ($db -> connect_errno > 0) { 
    $lbOK = false; 
  }
  else {
    $lbOK = $db -> set_charset('utf8');
  } 

  if ($lbOK) {
    $id         = NULL;
    $user_name  = NULL;
    $user       = htmlentities($user, ENT_QUOTES);
    $lcSQL      = "SELECT `user_name` FROM `users` WHERE user_name=?";
    $stmt       = $db -> prepare($lcSQL);
    $ok         = $stmt -> bind_param('s', $user);
    $ok         = $stmt -> execute();
    $ok         = $stmt -> bind_result($user_name);

    while ($row = $stmt -> fetch()){
      echo $user_name;
    }

    $stmt->close();
  }
}

1 个解决方案

#1

There are many major faults with your code, some of them can be responsible for the problem, and some not. But nevertheless, they all have to be corrected

您的代码存在许多主要缺陷,其中一些可能是问题的原因,而另一些则不是。但是,他们都必须得到纠正

Never connect co database inside of an application function. Connect somewhere in the bootstrap file, once, and use that single connection throughout all the application.

切勿在应用程序功能内部连接co数据库。在引导程序文件中的某处连接一次,并在整个应用程序中使用该单个连接。

Do not use htmlentities with whatever database interactions. It may easily spoil the data

不要将htmlentities与任何数据库交互一起使用。它可能很容易破坏数据

Always check for the the errors

始终检查错误

Do not use mysqli, it is unusable. Use PDO instead.

不要使用mysqli,它是无法使用的。请改用PDO。

$dsn = "mysql:host=DBHost;dbname=DBName;charset=utf8";
$opt = array(
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
);
$pdo = new PDO($dsn,$DBUser, $DBPass, $opt);

function requestUser($user) {
  global $db;

  $sql  = "SELECT `user_name` FROM `users` WHERE user_name=?";
  $stmt = $db->prepare($sql);
  $stmt->execute(array($user));
  return $stmt->fetchColumn();
}
echo requestUser($user);

if it still doesn't work, verify it this way

如果它仍然不起作用,请以这种方式验证

  $sql  = "SELECT `user_name` FROM `users` WHERE user_name='$user'";
  var_dump($sql);

and then try to run in console/phpmyadmin to find out what's wrong with your data/value

然后尝试在console / phpmyadmin中运行以找出您的数据/值有什么问题

1 个解决方案

#1

更多相关文章

随机推荐