按时间戳排序，然后将某些元素设置为第一答案

【问题标题】：Sort by timestamp, then set certain elements as first按时间戳排序，然后将某些元素设置为第一
【发布时间】：2021-03-11 16:21:58
【问题描述】：

鉴于这个集合：

$payments = [{
    "timestamp": "2021-03-10 21:19:10",
    "amount": "100",
    "currency":"eur"
},
{
    "timestamp": "2021-03-10 22:11:10",
    "amount": "100",
    "currency":"gbp"
},
{
    "timestamp": "2021-03-10 23:19:10",
    "amount": "100",
    "currency":"usd"
},
{
    "timestamp": "2021-03-10 22:19:10",
    "amount": "100",
    "currency":"gbp"
}]

我想以付款按时间戳排序的方式对其进行排序，但从某种货币开始。例如 gbp。

$payments = [{
    "timestamp": "2021-03-10 22:11:10",
    "amount": "100",
    "currency":"gbp"
},
{
    "timestamp": "2021-03-10 22:19:10",
    "amount": "100",
    "currency":"gbp"
}
{
    "timestamp": "2021-03-10 21:19:10",
    "amount": "100",
    "currency":"eur"
},
{
    "timestamp": "2021-03-10 23:19:10",
    "amount": "100",
    "currency":"usd"
}]

现在我正在以我首先采用货币为 gbp 的排序集合的方式进行操作，然后我将合并到货币为 not gbp 的排序集合。像这样：

$paymentsInSameCurrency = $payments
    ->where('currency',$currency)
    ->sortBy('timestamp');

$paymentsInDifferentCurrency = $payments
    ->where('currency','!=',$currency)
    ->sortBy('timestamp');

$payments = $paymentsInSameCurrency->merge($paymentsInDifferentCurrency);

有没有办法让它更有效率？

【问题讨论】：

标签： php laravel laravel-5

【解决方案1】：

简化版可能是这样的：

 $payments = $payments
    ->sortByDesc(\DB::raw("currency = '$currency'")); // first when it's true
    ->sortBy('timestamp');                            // second level sorting by timestamp

【讨论】：