Question

如果注册名称已经存在，我想停止用户注册。

这是我的代码：

<?php
$username = filter_input(INPUT_POST, 'name');
$password = md5(filter_input(INPUT_POST, 'password'));
print_r($_POST['name']);
if (empty($username)){
    echo "Username should not be empty"; die();
}
if (empty($password)){
    echo "Password should not be empty"; die();
}
$host = "localhost";
$dbusername = "root";
$dbpassword = "";
$dbname = "db_account";

//create connection
$conn = new mysqli($host, $dbusername, $dbpassword, $dbname);

// Check the database for duplicate username
$username_check_query = "SELECT * FROM t_account WHERE name='$username' LIMIT 1";
$result = mysqli_query($db, $user_check_query);
$username = mysqli_fetch_assoc($result);

if ($username) { // if user exists
    if ($username['name'] === $username) {
      echo "Username already exists"; die();
    }
}

// Register user
if (mysqli_connect_error()) {
    die('Connect Error ('. mysqli_connect_error() .') ' . mysqli_connect_error());
} else {
    $sql = "INSERT INTO t_account (name, pwd)
              VALUES('$username', '$password')";
    if ($conn->query($sql)){
      echo " Account created successfully!";
    }
    else{
      echo "Error: ". $sql."<br>". $conn->error;
    }
    $conn->close(); 
}
}
?>

我仍然是新手，所以我不知道它是否正确。我使用了模板中的一部分并进行了编辑。现在，当我尝试注册时，它会给我Error 500..

Answer 1

    <form action="" method="post">
  <input type="text" name="name">
  <input type="text" name="password">
  <button type="submit">send</button>
</form>
<?php
$username = filter_input(INPUT_POST, 'name');
$password = md5(filter_input(INPUT_POST, 'password'));
print_r($_POST['name']);
if (empty($username)){
    echo "Username should not be empty"; die();
}
if (empty($password)){
    echo "Password should not be empty"; die();
}
$host = "localhost"; 
$dbusername = "root";
$dbpassword = "";
$dbname = "db_account";

//create connection
$conn = new mysqli($host, $dbusername, $dbpassword, $dbname);

  // Check the database for duplicate username
  $username_check_query = "SELECT * FROM t_account WHERE name='$username' LIMIT 1";
  $result = mysqli_query($conn, $username_check_query);
  $username_from_db = mysqli_fetch_assoc($result);

  if ($username_from_db) { // if user 
    if ($username_from_db['name'] === $username) {
      echo "Username already exists"; die();
    }
  }

  // Register user
  if (mysqli_connect_error()){
    die('Connect Error ('. mysqli_connect_error() .') '
      . mysqli_connect_error());
  } else{
    $sql = "INSERT INTO t_account (name, pwd) 
              VALUES('$username', '$password')";
    if ($conn->query($sql)){
      echo " Account created successfully!";
    }
    else{
      echo "Error: ". $sql."<br>". $conn->error;
    }
    $conn->close();

  }

?>

发布新记录之前检查MySQL数据库是否重复

1 个答案: