Use of php pdo placeholder (explanation with code examples)

$dbms='mysql';//数据库类型
$host='localhost';//数据库主机名
$dbName='test';//使用的数据库
$user='root';//数据库连接用户名
$pass='root';//对应的密码
$dsn="$dbms:host=$host;dbname=$dbName"; 
try{
$db=newPDO($dsn,$user,$pass);//初始化一个PDO对象
}catch(PDOException$e){
die("Error!:".$e->getMessage()."
");
}
$username=isset($_GET['username'])?$_GET['username']:'';
$ip=isset($_GET['ip'])?$_GET['ip']:'';
$mac=isset($_GET['mac'])?$_GET['mac']:'';
$apMac=isset($_GET['apMac'])?$_GET['apMac']:'';
$loginTime=isset($_GET['loginTime'])?$_GET['loginTime']:'';
$time=date('Y-m-dH:i:s');
 
//编写sql使用占位符
$sql="insertintotest(username,ip,mac,apMac,loginTime,insert_time)
values(:username,:ip,:mac,:apMac,:loginTime,'$time')";
$query=$db->prepare($sql);
/**
感觉挺麻烦的
$query->bindParam(':username',$username);
$query->bindParam(':ip',$ip);
$query->bindParam(':mac',$mac);
$query->bindParam(':apMac',$apMac);
$query->bindParam(':loginTime',$loginTime);
$query->execute();
**/
$result=$query->execute(array(
    ':username'=>$username,
    ':ip'=>$ip,
    ':mac'=>$mac,
    ':apMac'=>$apMac,
    ':loginTime'=>$loginTime,
));