PHP检查用户是否存在PDO

Question

我想实现的功能，其中它会检查是否如果用户在我的数据库已经存在，是它会插入所有注册数据，但它似乎没有工作=（可能有人请帮我找出错误所在。真的很感谢所有的答案提前。

<?php 

require '../ppuyakul/php/db_conn.php'; 


$message = ''; 

//Prepare date 
$DOB = date("Y-m-d", strtotime($_POST['year'].'-'. $_POST['month'].'-'. $_POST['day'])); 
$accessType = "0"; 

//Check enpty field 
if(!empty($_POST['email']) && !empty($_POST['password']) && !empty($_POST['fullname']) && !empty($_POST['username']) && !empty($_POST['password_confirmation']) && !empty($_POST['gender']) && !empty($_POST['country']) && !empty($_POST['state']) && !empty($_POST['city']) && !empty($_POST['day']) && !empty($_POST['month']) && !empty($_POST['year'])): 

    // Enter the new user in the database 
    $sql = "INSERT INTO assignment2 (fullname, username, email, password, gender, country, state, city, DOB, type) VALUES (:fullname, :username, :email, :password, :gender, :country, :state, :city, :DOB, :type)"; 
    $stmt = $conn->prepare($sql); 

    $stmt->bindParam(':fullname', $_POST['fullname']); 
    $stmt->bindParam(':username', $_POST['username']); 
    $stmt->bindParam(':email', $_POST['email']); 
    $stmt->bindParam(':password', password_hash($_POST['password'], PASSWORD_BCRYPT)); 
    $stmt->bindParam(':gender', $_POST['gender']); 
    $stmt->bindParam(':country', $_POST['country']); 
    $stmt->bindParam(':state', $_POST['state']); 
    $stmt->bindParam(':city', $_POST['city']); 
    $stmt->bindParam(':DOB', $DOB); 
    $stmt->bindParam(':type', $accessType); 

    $chk = $conn->prepare("SELECT username FROM assignment2 WHERE username = :name"); 
    $chk->bindParam(':name', $username); 
    $chk->execute(); 

    if($chk->rowCount() > 0): 
    $message = 'Error ! ! User already exists'; 
    else: 
     if($stmt->execute()): 
     $message = 'Successfully created new user'; 
      else: 
      $message = 'Sorry there must have been an issue creating your account'; 
      endif; 
     endif; 
    endif; 
?> 

Answer 1

据@保罗T.我终于发现这里的解决方案是最后的代码，感谢这么多再次为你的帮助@ Paul T.

$username = $_POST['username']; 
    $chk = $conn->prepare("SELECT username FROM assignment2 WHERE username = :name"); 
    $chk->bindParam(':name', $username); 
    $chk->execute(); 


    if($chk->rowCount() > 0): 
    $message = 'Error ! ! User already exists'; 
    else: 
     if($stmt->execute()): 
     $message = 'Successfully created new user'; 
      else: 
      $message = 'Sorry there must have been an issue creating your account'; 
      endif; 
     endif; 
    endif;