Почему не работают некоторый SQL команды?

Вот мой код:

<?php
  session_start();

  $dsn = 'mysql:host=localhost;dbname=tsecret1_users;';
  $pdo = new PDO($dsn, 'tsecret1_Sys', 'i$Q5****.2m.');

//Переменные
  $email = $_POST['email'];
  $pass = $_POST['pass'];
  $pass2 = $_POST['pass2'];
  $pass2_hash = hash("sha256", $pass2);
  $session = hash("sha512", $email);
  $email_base64 = base64_encode($email);

  $sql = 'SELECT * FROM `Exiting Users` WHERE email = ?';
  $query = $pdo->prepare($sql);
  $query->execute([$email]);
  $row = $sql->fetchAll;

  $num_rows = count($row);
  echo $num_rows;
  if ($num_rows == 0) {
    if ($pass == $pass2) {
      //Регистрация
      $sql = 'INSERT INTO `Exiting Users`(`email`) VALUES (:email)';
      $query = $pdo->prepare($sql);
      $query->execute(["email" => $email]);

      $sql = 'CREATE TABLE `tsecret1_users`.`:email` ( `PassWord` TEXT NOT NULL ) ENGINE = MyISAM';
      $query = $pdo->prepare($sql);
      $query->execute(["email" => $email]);

      $sql = 'INSERT INTO `:email`(`PassWord`) VALUES (:pass2_hash)';
      $query = $pdo->prepare($sql);
      $query->execute(["email" => $email, "pass2_hash" => $pass2_hash]);

      $sql = 'ALTER TABLE `:email` ADD `parameters` TEXT NOT NULL AFTER `PassWord`';
      $query = $pdo->prepare($sql);
      $query->execute(["email" => $email]);

      $sql = 'INSERT INTO `?`(`parameters`) VALUES (`EmailIsNotVerified`)';
      $query = $pdo->prepare($sql);
      $query->execute([$email]);

      //Открытие сессии
      $sql = 'ALTER TABLE `:email` ADD `Sessions` TEXT NOT NULL AFTER `parameters`';
      $query = $pdo->prepare($sql);
      $query->execute(["email" => $email]);

      $sql = 'INSERT INTO `:email`(`Sessions`) VALUES (`:session`)';
      $query = $pdo->prepare($sql);
      $query->execute(["session" => $session]);
    }
  }
?>

Проблема: Не работают команды: $sql = 'INSERT INTO `:email`(`Sessions`) VALUES (`:session`)';

И $sql = 'INSERT INTO `?`(`parameters`) VALUES (`EmailIsNotVerified`)';

Спасибо за любую помощь