PDO从数据库获取数据

问题描述：

我最近开始使用PDO，之前我只是使用MySQL. 现在，我试图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.');
}

但是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.

答

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())
另外，您似乎并没有在调用 execute() 方法，在准备好语句后发生在之后，但实际上是在之前获取数据:

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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