在准备好的语句上使用 fetch_assoc (php mysqli)

问题描述

我目前正在编写一个登录脚本，我得到了这个代码:

I'm currently working on a login script, and I got this code:

$selectUser = $db->prepare("SELECT `id`,`password`,`salt` FROM `users` WHERE `username`=?");
$selectUser->bind_param('s', $username);
$selectUser->execute();

if ($selectUser->num_rows() < 0)
    echo "no_user";
else
{
    $user = $selectUser->fetch_assoc();
    echo $user['id'];
}

这是我得到的错误:

致命错误:未捕获的错误:调用未定义的方法mysqli_stmt::fetch_assoc()

Fatal error: Uncaught Error: Call to undefined method mysqli_stmt::fetch_assoc()

我尝试了各种变体，例如:

I tried all sorts of variations, like:

$result = $selectUser->execute();
$user = $result->fetch_assoc();

还有更多……没有任何效果.

and more... nothing worked.

推荐答案

那是因为 fetch_assoc 不是 mysqli_stmt 对象的一部分.fetch_assoc 属于 mysqli_result 类.可以使用mysqli_stmt::get_result先获取一个结果对象，然后调用fetch_assoc:

That's because fetch_assoc is not part of a mysqli_stmt object. fetch_assoc belongs to the mysqli_result class. You can use mysqli_stmt::get_result to first get a result object and then call fetch_assoc:

$selectUser = $db->prepare("SELECT `id`,`password`,`salt` FROM `users` WHERE `username`=?");
$selectUser->bind_param('s', $username);
$selectUser->execute();
$result = $selectUser->get_result();
$assoc = $result->fetch_assoc();

或者，您可以使用 bind_result 将查询的列绑定到变量并使用 fetch() 代替:

Alternatively, you can use bind_result to bind the query's columns to variables and use fetch() instead:

$selectUser = $db->prepare("SELECT `id`,`password`,`salt` FROM `users` WHERE `username`=?");
$selectUser->bind_param('s', $username);
$selectUser->bind_result($id, $password, $salt);
$selectUser->execute();
while($selectUser->fetch())
{
    //$id, $password and $salt contain the values you're looking for
}

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