db.createCollection('orders')
db.orders.insertMany([
   { _id: 1, cust_id: "Ant O. Knee", ord_date: new Date("2020-03-01"), price: 25, items: [ { sku: "oranges", qty: 5, price: 2.5 }, { sku: "apples", qty: 5, price: 2.5 } ], status: "A" },
   { _id: 2, cust_id: "Ant O. Knee", ord_date: new Date("2020-03-08"), price: 70, items: [ { sku: "oranges", qty: 8, price: 2.5 }, { sku: "chocolates", qty: 5, price: 10 } ], status: "A" },
   { _id: 3, cust_id: "Busby Bee", ord_date: new Date("2020-03-08"), price: 50, items: [ { sku: "oranges", qty: 10, price: 2.5 }, { sku: "pears", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 4, cust_id: "Busby Bee", ord_date: new Date("2020-03-18"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 5, cust_id: "Busby Bee", ord_date: new Date("2020-03-19"), price: 50, items: [ { sku: "chocolates", qty: 5, price: 10 } ], status: "A"},
   { _id: 6, cust_id: "Cam Elot", ord_date: new Date("2020-03-19"), price: 35, items: [ { sku: "carrots", qty: 10, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 7, cust_id: "Cam Elot", ord_date: new Date("2020-03-20"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 8, cust_id: "Don Quis", ord_date: new Date("2020-03-20"), price: 75, items: [ { sku: "chocolates", qty: 5, price: 10 }, { sku: "apples", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 9, cust_id: "Don Quis", ord_date: new Date("2020-03-20"), price: 55, items: [ { sku: "carrots", qty: 5, price: 1.0 }, { sku: "apples", qty: 10, price: 2.5 }, { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" },
   { _id: 10, cust_id: "Don Quis", ord_date: new Date("2020-03-23"), price: 25, items: [ { sku: "oranges", qty: 10, price: 2.5 } ], status: "A" }
])


db.orders.mapReduce(
   function() { emit(this.cust_id, this.price); },
   function(keyCustId, valuesPrices) {
      return Array.sum(valuesPrices);
   },
   { out: "map_reduce_example" }
)

db.map_reduce_example.find().sort( { _id: 1 } )

MongoDB online editor

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About MongoDB

MongoDB is a cross platform document oriented NoSQL database.

Key Features:

  • Designed to overcome the the limitations of relational databases approach and other NoSQL solutions
  • Horizontal scaling
  • Load balancing capabilities
  • Better data availability and stability

Syntax help

Commands

Inserting documents

  1. db.collection.insert(): Using insert you can either insert one document or array of documents
db.employees.insert(   {empId: 3, name: 'Ava', dept: 'Sales' });
  1. db.collection.insertOne(): Inserts one document
db.employees.insertOne(  {empId: 4, name: 'Nick', dept: 'Accounting' });
  1. db.collection.insertMany: Inserts multiple documents
db.employees.insertMany([
  {empId: 1, name: 'Clark', dept: 'Sales' },
  {empId: 2, name: 'Dave', dept: 'Accounting' }
]);

Updating documents

  1. db.collection.update() : Updates one or more than one document(s) in collection based on matching document and based on multi option
db.employees.update(   
  {empId: 3 },
  { $set: { region: "Asia" } }
);
  1. db.collection.updateOne() : Updates a single document in collection based on matching document
db.employees.updateOne(   
  {empId: 2 },
  { $set: { region: "Asia" } }
);
  1. db.collection.updateMany() : Updates multiple documents in collection based on the condition.
db.employees.updateMany(   
  { dept: 'Sales'},
  { $set: { region: "US" } }
);

Deleting documents

  1. db.collection.deleteOne(<filter>, <options>): Deletes a Single document from collection
db.employees.deleteOne({ empId: 1})
  1. db.collection.deleteMany(<filter>, <options>): Deletes all documents with matching filter
db.employees.deleteMany({ dept: 'Sales'})