prepare PDO

 

<?php
$sql='SELECT email FROM users WHERE id = :id';
$statement=$pdo->prepare($sql);
$userId=filter_input(INPUT_GET,'id');
$statement->bindValue(':id',$userId,PDO::PARAM_INT);
$statement->excute();

while(($result=$statement->fetch(PDO::FETCH_ASSOC))!==false)

　　{

　　　　echo $result['email'];

　　}