导入测试数据
测试数据地址:aggregation-data
导入方法:
wget https://github.com/tapdata/geektime-mongodb-course/raw/master/aggregation/dump.tar.gz
tar -xvf dump.tar.gz
mongorestore -h localhost:27017
聚合实验:总销量
计算到目前为止,所有订单的总销量
db.orders.aggregate([
{
$group: {
_id: null,
total: {
$sum: "$total",
},
},
},
]);
结果为:
{"_id": null,"total": NumberDecimal("44019609")}