如何使用 Laravel Eloquent 创建子查询

I have the following Eloquent query (This is a simplified version of a query which consists of of more wheres and orWheres hence the apparent roundabout way of going about this - the theory is what's important):

$start_date = //some date;

$prices = BenchmarkPrice::select('price_date', 'price')
->orderBy('price_date', 'ASC')
->where('ticker', $this->ticker)
->where(function($q) use ($start_date) {

    // some wheres...

    $q->orWhere(function($q2) use ($start_date){
        $dateToCompare = BenchmarkPrice::select(DB::raw('min(price_date) as min_date'))
        ->where('price_date', '>=', $start_date)
        ->where('ticker', $this->ticker)
        ->pluck('min_date');

        $q2->where('price_date', $dateToCompare);
    });
})
->get();

正如你所看到的，我知道最早的日期是在我start_date岁那年或之后.这将导致运行一个单独的查询来获取该日期，然后将该日期用作主查询中的参数.有没有一种方法可以Eloquent 地将查询嵌入到一起，形成一个子查询，从而只调用一个数据库调用，而不是两个？

Edit:

As per @Jarek's answer this is my query:

$prices = BenchmarkPrice::select('price_date', 'price')
->orderBy('price_date', 'ASC')
->where('ticker', $this->ticker)
->where(function($q) use ($start_date, $end_date, $last_day) {
    if ($start_date) $q->where('price_date' ,'>=', $start_date);
    if ($end_date) $q->where('price_date' ,'<=', $end_date);
    if ($last_day) $q->where('price_date', DB::raw('LAST_DAY(price_date)'));

    if ($start_date) $q->orWhere('price_date', '=', function($d) use ($start_date) {

        // Get the earliest date on of after the start date
        $d->selectRaw('min(price_date)')
        ->where('price_date', '>=', $start_date)
        ->where('ticker', $this->ticker);                
    });
    if ($end_date) $q->orWhere('price_date', '=', function($d) use ($end_date) {

        // Get the latest date on or before the end date
        $d->selectRaw('max(price_date)')
        ->where('price_date', '<=', $end_date)
        ->where('ticker', $this->ticker);
    });
});
$this->prices = $prices->remember($_ENV['LONG_CACHE_TIME'])->get();

这orWhere个块导致查询中的所有参数突然变得不带引号.例如，WHEREPrice_date>= 2009-09-07.当我删除orWheres时，查询运行正常.这是为什么呢？