准備的選擇語句和獲取結果

Question

我在“准備選擇語句”以及存儲和獲取結果方面遇到問題。 以下代碼允許用戶登錄。該代碼首先檢查數據庫中是否有匹配的記錄，然后將用戶重定向到“歡迎”頁面。 我很確定問題出在以下語句：$ stmt-> num_rows; 然后從$ stmt獲取結果。 任何幫助將不勝感激。

我有以下代碼：

 if ($user == "" || $pass == "")
{
$error = "<span class='error'>You must enter the username and password</span><br /><br />";

}
else
{
    $query = "SELECT UserName,Password,Role FROM Users
        WHERE UserName=? AND Password=?";


    $stmt = $db->prepare($query);
    $stmt->bind_param("ss", $user, $pass);
    $stmt->execute();
    $stmt->store_result();

   $stmt->num_rows;


    if ($stmt == 0) 
    {
        $error = "<span class='error'>Incorrect Username/Password
                  </span><br /><br />";
    }
    else
    {    for ($i=0; $i <$stmt; $i++) {
    $row = $stmt->fetch_assoc();
    $role = $row['Role'];

        $_SESSION['user'] = $user;
        $_SESSION['pass'] = $pass;
        $_SESSION['role'] = $role;

       header( "Location: welcome.php" ); //will redirect to pool list after succesful login
        die ("You are now logged in. ");
       }
    }
  }
}

Answer 1

看來我想通了。 代碼如下：

    $query = "SELECT UserName,Password,Role FROM Users
        WHERE UserName=? AND Password=?";


    $stmt = $db->prepare($query);
    $stmt->bind_param("ss", $user, $pass);
    $stmt->execute();
    $stmt->store_result();
    $numrows = $stmt->num_rows;
    $stmt->bind_result($user, $pass, $role);



    if ($numrows == 0) 
    {
        $error = "<span class='error'>Incorrect Username/Password
                  </span><br /><br />";
    }
    else
    {    for ($i=0; $i <$numrows; $i++) {
    $row = $stmt->fetch();


        $_SESSION['user'] = $user;
        $_SESSION['pass'] = $pass;
        $_SESSION['role'] = $role;

       header( "Location: welcome.php" ); //will redirect to pool list after succesful login
        die ("You are now logged in. Please <a href='members.php?view=$user'>" .
            "click here</a> to continue.<br /><br />");