mysql - 按日期排序进行分组

Question

我收到了按日期排序的用户的最新未读消息:

$messages = Message::whereReceiver(Auth::user()->id)->whereRead(0)->orderBy('sent', 'desc')->get();

输出是:

Array
(
    [0] => Array
        (
            [id] => 17
            [suggest_id] => 5
            [content] => How are you?
            [receiver] => 1
            [sent] => 2014-02-05 18:50:37
            [read] => 0
        )

    [1] => Array
        (
            [id] => 16
            [suggest_id] => 5
            [content] => Hi
            [receiver] => 1
            [sent] => 2014-02-05 18:09:15
            [read] => 0
        )
)

但是当我执行groupBy时，结果将不再降序:

$messages = Message::whereReceiver(Auth::user()->id)->whereRead(0)->orderBy('sent', 'desc')->groupBy('suggest_id')->get();

输出:

Array
(
    [0] => Array
        (
            [id] => 16
            [suggest_id] => 5
            [content] => Hi
            [receiver] => 1
            [sent] => 2014-02-05 18:09:15
            [read] => 0
        )
)

但是我希望输出日期为 2014-02-05 18:50:37 的消息!

Answer 1

这可能是一种替代方案(如果您只想收到一条/第一条消息)

Message::whereReceiver(Auth::user()->id)
       ->whereRead(0)
       ->orderBy('sent', 'desc')
       ->take(1) // Just get the top/first one from the set, ordered by desc
       ->get();

如果您想获取所有未读消息，那么(您已经拥有了)

Message::whereReceiver(Auth::user()->id)
       ->whereRead(0)
       ->orderBy('sent', 'desc')
       ->get();