我應該在哪里添加代碼以便它檢查電子郵件是否存在？

Question

我應該在哪里添加代碼以便它檢查電子郵件是否存在？ 我已將所有詳細信息插入數組中，我應該如何調用特定屬性以及應該在哪里實現它，以便它檢查我的數據庫中是否存在不止一封電子郵件？

<?php
        $connect = new PDO("mysql:host=localhost;dbname=testing", "root", "");
        $message = '';
        if(isset($_POST["email"]))
        {
         sleep(3); 
         $query = "
         INSERT INTO tbl_login 
         (first_name, last_name, gender, email, password, address, mobile_no) VALUES 
         (:first_name, :last_name, :gender, :email, :password, :address, :mobile_no)
         ";
         $password_hash = password_hash($_POST["password"], PASSWORD_DEFAULT); 
         
         $user_data = array(
          ':first_name'  => $_POST["first_name"],
          ':last_name'  => $_POST["last_name"],
          ':gender'   => $_POST["gender"],
          ':email'   => $_POST["email"],
          ':password'   => $password_hash,
          ':address'   => $_POST["address"],
          ':mobile_no'  => $_POST["mobile_no"]
        );
         $statement = $connect->prepare($query); 
         if($statement->execute($user_data)) 
         {
          $message = '
          <div class="alert alert-success">
          Registration Completed Successfully
          </div>
          ';
          header("location:login.php");
        }
        else
        {
          $message = '
          <div class="alert alert-success">
          There is an error in Registration
          </div>
          ';
        }
        }
        ?>

Answer 1

您可以編寫一個 if 語句來執行查詢並將結果值存儲到變量中。 現在，如果該變量為空，則表示數據庫尚未注冊相同的電子郵件。

$sql = 'SELECT email from tbl_login WHERE email=:email' 
$params = [
    :email => $_POST['email']
] ;

// Now the if statement which checks if the entered email already exists in the DB
$stmt = $connect->prepare($sql)
$stmt->execute($params) 
if(!$temp = $stmt->fetc()) 
{ // Email doesn't exist in the DB, procees to insert it} 
else
{ // Email already exists in the DB}