PDO选择$ _POST [关闭]

Question

this works just fine

$db = new PDO(<connection data>);
    $username = $_POST['username'];
    $password = $_POST['password'];
    if(isset($_POST['username']) && isset($_POST['password'])){
        $username = "name";
        $pw = $db->prepare('SELECT * FROM table WHERE column1 = ?');
        $pw->execute(array($username));
        $result = $pw->fetchAll();
        var_dump($result);
    }

If i use $_POST['username'] after form submission i get array(0) { } for var_dump($result);

$db = new PDO(<connection data>);
    $username = $_POST['username'];
    $password = $_POST['password'];
    if(isset($_POST['username']) && isset($_POST['password'])){
        $username = $_POST['username'];
        //var_dump($username); --> string(7) " name"
        $pw = $db->prepare('SELECT * FROM table WHERE column1 = ?');
        $pw->execute(array($username));
        $result = $pw->fetchAll();
        var_dump($result);
    }

Do you see where i made my mistake(s)?

Answer 1

In the first test, with hard-coded value, you have

$username = "name";

then, when using post value, it becomes

$username = $_POST['username']; // --> " name"

as you see, there is an extra space. If such space should not be there, you could then try trimming the value, like:

$username = trim($_POST['username']);

However, if having spaces in username is an error, you should not "correct" it yourself, and just report the error to the user (I think this is more a UX aspect than a programming one).