PHP文件检查数据库中是否存在电子邮件[重复]

Question

我正在尝试检查我的数据库中是否已经存在电子邮件，我认为我有正确的代码可以检查，但由于某种原因，我仍然可以使用相同的电子邮件创建另一个用户。我想同时检查用户名和电子邮件。

这是我目前拥有的代码：

<?php
  if (empty($username) || empty($email) || empty($pwd) || empty($pwdcheck)){
    header("Location: ../cadastrar.php?error=emptyfields&nome=".$username."&email=".$email);
    exit();
  }else if(!filter_var($email, FILTER_VALIDATE_EMAIL) && !preg_match("/^[a-zA-Z0-9]*$/", $username)){
    header("Location: ../cadastrar.php?error=invalidmailusername");
    exit();
  }else if(!filter_var($email, FILTER_VALIDATE_EMAIL)){
    header("Location: ../cadastrar.php?error=invalidmail&nome=".$username);
    exit();
  }else if(!preg_match("/^[a-zA-Z0-9]*$/", $username)){
    header("Location: ../cadastrar.php?error=invalidusername&email=".$email);
    exit();
  }else if($pwd !== $pwdcheck){
    header("Location: ../cadastrar.php?error=passwordcheck&email=".$email."&nome=".$username);
    exit();
  }else{
    $sql = "SELECT usuario FROM users WHERE usuario=?";
    $stmt = mysqli_stmt_init($conn);
    if (!mysqli_stmt_prepare($stmt, $sql)){
      header("Location: ../cadastrar.php?error=sqlerror");
      exit();
    }else{
      mysqli_stmt_bind_param($stmt, "s", $username);
      mysqli_stmt_execute($stmt);
      mysqli_stmt_store_result($stmt);
      $resultCheck = mysqli_stmt_num_rows($stmt);
      if ($resultCheck > 0){
        header("Location: ../cadastrar.php?error=usertaken&email=".$email);
        exit();
      }else{
        $sql = "INSERT INTO users (nomecompleto ,usuario, emailuser, pwdusers) VALUES (?, ?, ?, ?)";
        $stmt = mysqli_stmt_init($conn);
        if (!mysqli_stmt_prepare($stmt, $sql)){
          header("Location: ../cadastrar.php?error=sqlerror");
          exit();
        }else{
          $hashedpwd = password_hash($pwd, PASSWORD_DEFAULT);

          mysqli_stmt_bind_param($stmt, "ssss", $nomecompleto, $username, $email , $hashedpwd);
          mysqli_stmt_execute($stmt);
          header("Location: ../cadastrar.php?cadastro=sucesso");
          exit();
        }
      }
    }
  }
  mysqli_stmt_close($stmt);
  mysqli_close($conn);
}else{
  header("Location: ../cadastrar.php");
  exit();
}

Answer 1

您应该将$sql = "SELECT usuario FROM users WHERE usuario=?"; 中的usuario=? 替换为emailuser=?，并将绑定值替换为$email。您当前不是在检查电子邮件，而是在检查姓名。