php - 对index.php中的非对象调用成员函数fetch()

Question

        $sql = $db->query('SELECT `xp`,`deposits`,`withdraws`,`zeros`,`wins`,`daily` FROM `users` WHERE `steamid` = ' . $db->quote($user['steamid']));
    $row = $sql->fetch();
    $profile['xp'] = $row['xp'];
    $profile['deposits'] = $row['deposits'];
    $profile['withdraws'] = $row['withdraws'];
    $profile['zeros'] = $row['zeros'];
    $profile['level'] = LevelFromXP($row['xp'])[0];
    $profile['level_name'] = LevelFromXP($row['xp'])[1];
    $profile['rank'] = RankFromWins($row['wins']);
    $profile['bet_wins'] = $row['wins'];
    if ($row['daily'] == "0") {
        if (explode(" | ", $user['name'])[1] == "mysitehehe.com") {
            $daily = 1;
        } else {
            $daily = -1;
        }
    } elseif ($row['daily'] < time()) {
        $daily = 1;
    } else {
        $daily = 0;
        $profile['dailywait'] = $row['daily'] - time();
    }


    $page = getTemplate('main.tpl', array('page' => $_GET['page'], 'db' => $db, 'user' => $user, 'profile' => $profile, 'daily' => $daily, 'happyhour' => $happyhour, 'settings' => $settings));
    echo $page;
    break;

为什么我会收到此错误？ fatal error :在第 420 行对 index.php 中的非对象调用成员函数 fetch()

Answer 1

您的查询失败，因此 $sql 是 bool 值 false，而不是您可以调用 fetch 的查询结果。

在使用结果之前应该检查查询是否成功

$sql = $db->query('SELECT `xp`,...');
if(!$sql){
    //DB error: prob bad query or wrong connection credentials
    die($sql->error);
}
elseif($sql->num_rows===0){
    // 0 record found
}
else{
   $row = $sql->fetch();
   ...
}