Mysql 仅登录第一个用户错误

Iam使用PHP5.5和pdo创建登录代码。代码运行良好，但唯一的第一个用户登录我不知道为什么？例如，我的数据库表中有5个用户。当我登录第一个时，它会转到LogeIn，但当我尝试登录第二个或第三个时，它会显示一条错误消息，我设置的数据登录不正确。下面是我的登录码

<?php
session_start();
include 'conn.php';
try
{
    $user = $_POST['user'];
    $pass = $_POST['pass'];
    $remember=$_POST['remember'];
        $smt=$conn->prepare("SELECT * FROM signup");
        $smt->execute();
        $result=$smt->fetch(PDO::FETCH_OBJ);
        $prev=$result->Password;
    $usr=$result->Username;

        if(password_verify($pass,$prev)& $user===$usr)
        {
        // Set username session variable
        $_SESSION['user'] = $user;
        // Jump to secured page
        header('location:index.php');
    }


    else
    {

        header('location:signin.php');
        $_SESSION['login']="Incorrect username or password";
    }

    if($remember)
    {
        setcookie('remember-me',$user,time()+3600000);
        setcookie('remember-pass',$pass,time()+3600000);
        header('location:index.php');

    }
    else
    {
        setcookie('remember-me',$user,false);
        setcookie('remember-pass',$pass,false);


    }

}
catch(PDOException $e)
{
    throw new PDOException($e);
}

?>

---

提前感谢…

您缺少一个

WHERE子句

：

SELECT * FROM signup WHERE Username = :user

将代码调整为以下值：

$smt=$conn->prepare("SELECT * FROM signup WHERE Username =:user");
$smt->execute(array(':user'=>$user));

---

请用下面的代码更新您的代码

<?php
session_start();
include 'conn.php';
try
{
    $user = $_POST['user'];
    $pass = $_POST['pass'];
    $remember=$_POST['remember'];
        $smt=$conn->prepare("SELECT * FROM signup WHERE username = '".$user."' AND password = '".$pass."' ");
        $smt->execute();
        $result=$smt->fetch(PDO::FETCH_OBJ);
        $prev=$result->Password;
    $usr=$result->Username;

        if(password_verify($pass,$prev)& $user===$usr)
        {
        // Set username session variable
        $_SESSION['user'] = $user;
        // Jump to secured page
        header('location:index.php');
    }


    else
    {

        header('location:signin.php');
        $_SESSION['login']="Incorrect username or password";
    }

    if($remember)
    {
        setcookie('remember-me',$user,time()+3600000);
        setcookie('remember-pass',$pass,time()+3600000);
        header('location:index.php');

    }
    else
    {
        setcookie('remember-me',$user,false);
        setcookie('remember-pass',$pass,false);


    }

}
catch(PDOException $e)
{
    throw new PDOException($e);
}

?>