不懂就问，这么写，是不是很费资源。。。

原来

$merchants = Merchant::where('ident_status',10)
                        ->select('id', 'company_name', 'store_pic', 'goods_category', 'location_name', 'latitude', 'longitude')
                        ->selectRaw(\DB::raw('(6371 * acos(cos(radians(' . $userLatitude . ')) * cos(radians(latitude)) * cos(radians(longitude) - radians(' . $userLongitude . ')) + sin(radians(' . $userLatitude . ')) * sin(radians(latitude)))) AS distance'))
                        ->with('merchant_goods:id,merchant_id,merchant_goods_total_price,merchant_goods_sell_price,merchant_goods_title')
                        ->orderBy('created_at', 'desc')
                        ->paginate(10);

其中，下面是在算用户和商户的实时距离

selectRaw(\DB::raw('(6371 * acos(cos(radians(' . $userLatitude . ')) * cos(radians(latitude)) * cos(radians(longitude) - radians(' . $userLongitude . ')) + sin(radians(' . $userLatitude . ')) * sin(radians(latitude)))) AS distance'))

现在更复杂了

merchant 和 merchant_goods 两张表，要在merchant计算距离，要在merchant_goods统计商户的所有商品销量，还要列出merchant对应的所有merchant_goods，

$merchantsQuery = Merchant::join('merchant_goods', 'merchants.id', '=', 'merchant_goods.merchant_id')
                    ->where('merchants.ident_status', 10)
                    ->has('merchant_goods')
                    ->select('merchants.id', 'merchants.user_id', 'merchants.company_name', 'merchants.store_pic', 'merchants.goods_category', 'merchants.location_name', 'merchants.latitude', 'merchants.longitude')
                    ->selectRaw(\DB::raw('(6371 * acos(cos(radians(' . $userLatitude . ')) * cos(radians(merchants.latitude)) * cos(radians(merchants.longitude) - radians(' . $userLongitude . ')) + sin(radians(' . $userLatitude . ')) * sin(radians(merchants.latitude)))) AS distance'))
                    ->selectRaw('SUM(merchant_goods.fake_sell_count) AS fake_sell_count')
                    ->groupBy('merchants.id', 'merchants.user_id', 'merchants.company_name', 'merchants.store_pic', 'merchants.goods_category', 'merchants.location_name', 'merchants.latitude', 'merchants.longitude')
                    ->with('merchant_goods:id,merchant_id,merchant_goods_total_price,merchant_goods_sell_price,merchant_goods_title');

        if($category == 'default') {
            $merchantsQuery->orderBy('merchants.created_at', 'desc');
        }

        if($category == 'lbs') {
            $merchantsQuery->orderBy('distance', 'asc');
        }

        if($category == 'sell') {
            $merchantsQuery->orderBy('fake_sell_count', 'desc');
        }

        $merchants = $merchantsQuery->paginate(7);

model优化版(计算在model里了，但是速度更慢了，同时100条1.2s，直接写sql里算900ms左右)

public function list(Request $request) {

        $category = $request->category;

        $userLatitude = $request->latitude;

        $userLongitude = $request->longitude;

        //select、with的时候id或者ORM匹配的字段一定要有，不然with会失效
        $merchantsQuery = Merchant::join('merchant_goods', 'merchants.id', '=', 'merchant_goods.merchant_id')
                    ->where('merchants.ident_status', 10)
                    ->has('merchant_goods')
                    ->select('merchants.id', 'merchants.user_id', 'merchants.company_name', 'merchants.store_pic', 'merchants.goods_category', 'merchants.location_name', 'merchants.latitude', 'merchants.longitude')
                    ->selectRaw('SUM(merchant_goods.fake_sell_count) AS fake_sell_count')
                    ->groupBy('merchants.id', 'merchants.user_id', 'merchants.company_name', 'merchants.store_pic', 'merchants.goods_category', 'merchants.location_name', 'merchants.latitude', 'merchants.longitude')
                    ->with('merchant_goods:id,merchant_id,merchant_goods_total_price,merchant_goods_sell_price,merchant_goods_title');

        // 在这里输出$merchants之前，可以对其进行遍历，计算每个商家距离用户的距离
        foreach ($merchantsQuery->get() as $merchants) {
            $merchants->distance; // 访问距离属性，会触发getDistanceAttribute()方法进行计算
        }

        if($category == 'default') {
            $merchantsQuery->orderBy('merchants.created_at', 'desc');
        }

        if($category == 'lbs') {
            $merchantsQuery->orderBy('merchants.distance', 'asc');
        }

        if($category == 'sell') {
            $merchantsQuery->orderBy('fake_sell_count', 'desc');
        }

        $merchants = $merchantsQuery->paginate(100);

        return response()->json(['data' => $merchants],201);

    }