Laravel：如何在按升序排序后获取最后 n（任意数量）行？
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Laravel : How to take last n(any number) rows after ordered in ascending order?
提问by Mark
- I have 3 columns
id,msgandcreated_atin my Model table.created_atis a timestamp andidis primary key. - I also have 5 datas,
world => time4,hello => time2,haha => time1,hihio => time5anddunno => time3and these datas are arranged in ascending order (as arranged here) based on theirid.
- 我有3列
id，msg并created_at在我的模型表。created_at是时间戳，id是主键。 - 我也有5个DATAS， ，
world => time4，，和这些的数据都是按升序排列根据他们（这里安排）。hello => time2haha => time1hihio => time5dunno => time3id
In laravel 4, I want to fetch these data, arrange them in ascending order and take the last n(in this case, 3) number of records. So, I want to get dunno,worldand hihiorows displayed like this in a div :
在 laravel 4 中，我想获取这些数据，按升序排列它们并获取最后 n（在本例中为 3）条记录。所以，我想在 div 中获取dunno,world和这样hihio显示的行：
dunno,time3
world,time4
hihio,time5
What I have tried
我试过的
Model::orderBy('created_at','asc')->take(3);
undesired result :
不想要的结果：
haha,time1
hello,time2
dunno,time3
Also tried
也试过
Model::orderBy('created_at','desc')->take(3);
undesired result :
不想要的结果：
hihio,time5
world,time4
dunno,time3
I have also tried the reverse with no luck
我也试过相反的但没有运气
Model::take(3)->orderBy('created_at','asc');
This problem seems fairly simple but I just can't seem to get my logic right. I'm still fairly new in Laravel 4 so I would give bonus points to better solutions than using orderBy()and take()if there is. Thank you very much!
这个问题看起来很简单，但我似乎无法正确理解我的逻辑。我在 Laravel 4 中还是个新手，所以我会给比使用更好的解决方案加分orderBy()，take()如果有的话。非常感谢！
采纳答案by Tim Groeneveld
You are very close.
你很亲近。
It sounds like you want to first order the array by descending order
听起来您想先按降序对数组进行排序
Model::orderBy('created_at','desc')->take(3);
but then reverse the array. You can do this one of two ways, either the traditional PHP (using array_reverse).
但随后反转数组。您可以通过两种方式之一执行此操作，即传统的 PHP（使用 array_reverse）。
$_dates = Model::orderBy('created_at','desc')->take(3);
$dates = array_reverse($_dates);
Or the laravel way, using the reversefunction in Laravel's Collectionclass.
或者 Laravel 方式，使用reverseLaravelCollection类中的函数。
$_dates = Model::orderBy('created_at','desc')->take(3)->reverse();
Check out Laravel's Collectiondocumentation at their API site at http://laravel.com/api/class-Illuminate.Support.Collection.html
Collection在http://laravel.com/api/class-Illuminate.Support.Collection.html的 API 站点上查看 Laravel 的文档
Now $dates will contain the output you desire.
现在 $dates 将包含您想要的输出。
dunno,time3
world,time4
hihio,time5
回答by Kemal Fadillah
You're pretty close with your second attempt. After retrieving the rows from the database, you just need to reverse the array. Assuming you have an instance of Illuminate\Support\Collection, you just need to the following:
您已经非常接近第二次尝试了。从数据库中检索行后，您只需要反转数组。假设您有一个 实例Illuminate\Support\Collection，您只需要执行以下操作：
$expectedResult = $collection->reverse();
回答by Riowaldy Indrawan
$reverse = Model::orderBy('created_at','desc')->take(3);
$reverse = Model::orderBy('created_at','desc')->take(3);
$show = $reverse->reverse();
$show = $reverse->reverse();
