MongoDB とは？

➜ atlas setup
? Do you want to setup your Atlas database with default settings? (Y/n)
➜ Y
We are deploying Cluster9876543...
Please store your database authentication access details in a secure location.
Database User Username: Cluster9876543
Database User Password: abcdef12345
Creating your cluster... [Its safe to 'Ctrl + C']

test> db.orders.insertMany([
   { "item" : "almonds", "price" : 12, "quantity" : 2 },
   { "item" : "pecans", "price" : 20, "quantity" : 1 },
])
test> db.inventory.insertMany([
   { "sku" : "almonds", "description": "product 1", "instock" : 120 },
   { "sku" : "cashews", "description": "product 3", "instock" : 60 },
   { "sku" : "pecans", "description": "product 4", "instock" : 70 }
])
test> db.orders.aggregate([
   { $match: { price: { $lt: 15 } } },
   { $lookup: {
         from: "inventory",
         localField: "item",
         foreignField: "sku",
         as: "inventory_docs"
   } },
   { $sort: { price: 1 } },
])