Php 检查用户名是否存在PDO

我如何才能检查多个因素的组合，而不是检查每个因素？所以基本上我使用PDO，我必须确保用户名和电子邮件是唯一的。那我该怎么做呢？我见过

if ( $sthandler->rowCount() > 0 ) {
// do something here
}  

但是有没有更好的方法呢。还有，如果没有人能解释一下我是如何处理这个问题的

编辑 这是我输入数据库的查询代码

        <?php
try {
    $handler = new PDO('mysql:host=localhost;dbname=s','root', '*');
    $handler->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e){
    exit($e->getMessage());
}

$name = $_POST['name']; 
$username = $_POST['username']; 
$email = $_POST['email'];   
$password = $_POST['password']; 
$password1 = $_POST['passwordconf'];
$ip = $_SERVER['REMOTE_ADDR'];

//Verifcation 
if (empty($name) || empty($username) || empty($email) || empty($password) || empty($password1))
    {
    echo "Complete all fields";
    }

// Password match
if ($password != $password1)
    {
    echo $passmatch = "Passwords don't match";
    }

// Email validation

if (!filter_var($email, FILTER_VALIDATE_EMAIL))
    {
    echo $emailvalid = "Enter a  valid email";
    }

// Password length
if (strlen($password) <= 6){
    echo $passlength = "Choose a password longer then 6 character";
}





function userExists($db, $user)
{
    $userQuery = "SELECT * FROM userinfo u WHERE u.user=:user;";
    $stmt = $db->prepare($userQuery);
    $stmt->execute(array(':user' => $user));
    return !!$stmt->fetch(PDO::FETCH_ASSOC);
}

$user = 'userName';
$exists = userExists($db, $user);
if(exists)
{
     // user exists already.
}
else
{
     // user doesn't exist already, you can savely insert him.
}
if(empty($passmatch) && empty($emailvalid) && empty($passlength)) {

//Securly insert into database
$sql = 'INSERT INTO userinfo (name ,username, email, password, ip) VALUES (:name,:username,:email,:password,:ip)';    
$query = $handler->prepare($sql);

    $query->execute(array(

    ':name' => $name,
    ':username' => $username,
    ':email' => $email,
    ':password' => $password,
    ':ip' => $ip

    ));
    }
?>

---

您显示的代码对于检查用户名和电子邮件是否唯一没有多大意义。您应该在数据库上设置
唯一键。
类似的操作应该可以：

 <?php
//Connections
try {
    $handler = new PDO('mysql:host=localhost;dbname=s','root', '*');
    $handler->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e){
    exit($e->getMessage());
}

$name = $_POST['name']; 
$username = $_POST['username']; 
$email = $_POST['email'];   
$password = $_POST['password']; 
$password1 = $_POST['passwordconf'];
$ip = $_SERVER['REMOTE_ADDR'];


//Verifcation 
if (empty($name) || empty($username) || empty($email) || empty($password) || empty($password1)){
    $error = "Complete all fields";
}

// Password match
if ($password != $password1){
    $error = "Passwords don't match";
}

// Email validation

if (!filter_var($email, FILTER_VALIDATE_EMAIL)){
    $error = "Enter a  valid email";
}

// Password length
if (strlen($password) <= 6){
    $error = "Choose a password longer then 6 character";
}

if(!isset($error)){
//no error
$sthandler = $handler->prepare("SELECT username FROM users WHERE username = :name");
$sthandler->bindParam(':name', $username);
$sthandler->execute();

if($sthandler->rowCount() > 0){
    echo "exists! cannot insert";
} else {
    //Securly insert into database
    $sql = 'INSERT INTO userinfo (name ,username, email, password, ip) VALUES (:name,:username,:email,:password,:ip)';    
    $query = $handler->prepare($sql);

    $query->execute(array(

    ':name' => $name,
    ':username' => $username,
    ':email' => $email,
    ':password' => $password,
    ':ip' => $ip

    ));
    }
}else{
    echo "error occured: ".$error;
    exit();
}

function userExists($db, $user)
{
    $userQuery = "SELECT * FROM userinfo u WHERE u.user=:user;";
    $stmt = $db->prepare($userQuery);
    $stmt->execute(array(':user' => $user));
    return !!$stmt->fetch(PDO::FETCH_ASSOC);
}

$user = 'userName';
$exists = userExists($db, $user);
if(exists)
{
     // user exists already.
}
else
{
     // user doesn't exist already, you can savely insert him.
}

显示更多的代码。实际情况并非如此。确保输入有效后，我将其插入数据库。我仍将添加更多内容，为什么没有意义？您应该尝试进行
INSERT
，如果数据已经存在，则检查错误。如果您想通过以下步骤来实现：
1
检查是否有该用户名/电子邮件的条目
2
如果没有，请插入-有时您可以在两个会话中同时获得两个条目（通常发生在用户快速提交表单两次的情况下），这样我就可以使用所有条目了吗？我还用更多的代码编辑了我的帖子哦，我明白你的意思了，我修改了你的代码，添加了logic@user3574362Hmm。似乎没有输入，现在没有输入到数据库，也没有回显错误消息Yes。我现在已经添加了完整的代码。以防万一，这可能是我没有表现出的导致问题的原因。现在效果很好。那电子邮件呢。我会对电子邮件做同样的事情吗？我真的不确定在代码中修改什么才能使它适用于我的代码。我有一个编辑，如果你能帮助我，那将是greatI想知道你是否试图理解它。您应该已经将用户更改为用户名，您应该能够理解这一点。