按值的唯一数组

$email_users[] = $row;
print_r($email_users);

结果：

Array ( 
[0] => Array ( 
[user_id] => 87436 
[username] => Admin 
[user_email] => email@online.us 
[user_lang] => de 
[allowed] => 1 ) 
[1] => Array ( 
[user_id] => 68013 
[username] => Testuser 
[user_email] => email2@online.us 
[user_lang] => de 
[allowed] => 1 ) 
[2] => Array ( 
[user_id] => 68013 
[username] => Testuser 
[user_email] => email2@online.us 
[user_lang] => de 
[allowed] => 1 ) 
)

如您所见，user_id 68013是双倍的。我必须删除双数组。结果应如下所示：

Array ( 
[0] => Array ( 
[user_id] => 87436 
[username] => Admin 
[user_email] => email@online.us 
[user_lang] => de 
[allowed] => 1 ) 
[1] => Array ( 
[user_id] => 68013 
[username] => Testuser 
[user_email] => email2@online.us 
[user_lang] => de 
[allowed] => 1 ) 
)

我阅读并尝试了在堆栈上找到的几种解决方案。例如：

如何在多维数组中获取唯一值

$email_users[] = $row;
$user_ids = array();
foreach ($email_users as $h) {
$user_ids[] = $h['user_id'];
}
$email_users = array_unique($user_ids);
print_r($email_users);

但print_r只是：

Array ( [0] => 87436 [1] => 68013 )

谢谢你的时间。