PDO 从数据库中获取数据

2021-12-19 00:00:00 while-loop select fetch php pdo

我最近开始使用 PDO，之前我只使用 MySQL.现在我正在尝试从数据库中获取所有数据.

I started using PDO recently, earlier I was using just MySQL. Now I am trying to get all data from database.

$getUsers = $DBH->prepare("SELECT * FROM users ORDER BY id ASC");
$getUsers->fetchAll();
if(count($getUsers) > 0){
    while($user = $getUsers->fetch()){
        echo $user['username']."<br/>";
    }
}else{
    error('No users.');
}

但它没有显示任何用户，只是一个空白页面.

But it is not showing any users, just a blank page.

推荐答案

PDO 方法 fetchAll() 返回一个数组/结果集，您需要将其分配给一个变量，然后使用/迭代该变量:

The PDO method fetchAll() returns an array/result-set, which you need to assign to a variable and then use/iterate through that variable:

$users = $getUsers->fetchAll();
foreach ($users as $user) {
    echo $user['username'] . '<br />';
}

更新(缺少execute())
此外，您似乎没有调用 execute() 方法需要在之后你准备语句但之前你实际获取数据:

UPDATE (missing execute())
Also, it appears you aren't calling the execute() method which needs to happen after you prepare the statement but before you actually fetch the data:

$getUsers = $DBH->prepare("SELECT * FROM users ORDER BY id ASC");
$getUsers->execute();
$users = $getUsers->fetchAll();
...

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