Php 循环后的逗号

我想给每个用户名加一个逗号，除了最后一个。 例如：User1、User2、User3 我该怎么做？这是我的密码：

$user_online_sql = $db->query("SELECT DISTINCT account_id FROM online WHERE account_id != '-1';");
$users = '';
while ($user_online_row = mysql_fetch_array($user_online_sql)) {
$users .= $user->name($user_online_row['account_id']) . ' ';
}

我尝试了内爆函数，但它只输出了一个空白结果，以下是内爆函数的代码：

 $user_online_sql = $db->query("SELECT DISTINCT account_id FROM online WHERE account_id != '-1';");
$users = '';
while ($user_online_row = mysql_fetch_array($user_online_sql)) {
$users .= implode(', ',$user->name($user_online_row['account_id'])) . ' ';
} 

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使用

内爆

是对的，但你做得不对

$users = []; // or array() in PHP 5.3 and older
while($user_online_row = mysql_fetch_assoc($user_online_sql)) {
    $users[] = $user->name($user_online_row['account_id']);
}
$users = implode(", ",$users);
echo $users;

---

只需在每个用户之后添加一个逗号，并删除后面的逗号

$user_online_sql = $db->query("SELECT DISTINCT account_id FROM online WHERE account_id != '-1';");
$users = '';
while ($user_online_row = mysql_fetch_array($user_online_sql)) {
$users .= $user->name($user_online_row['account_id']).',';
}
rtrim ($users, ",");