MongoDB shell basics

Make sure to have MongoDB installed on your system and the daemon running.

To open the shell, type mongo and hit enter.

$ mongo
MongoDB shell version: 2.4.6
connecting to: test

You're now in the context of the database test. To list all the databases, use show dbs.

> show dbs
local	0.078125GB
test	0.203125GB

To create a new database or switch to an already existing one, utilize use.

> use mydb
switched to db mydb

Once you have switched to mydb, you can create a collection. Here we create a new named shapes.

> db.createCollection("shapes")
{ "ok" : 1 }

To prove that a new collection really has been created, you can list all the collections in the database.

> show collections
shapes
system.indexes

When you've created a collection, you can start inserting documents. Here we insert two shapes.

> db.shapes.insert({ "type": "rectangle", "width": 5, "height": 7 })
> db.shapes.insert({ "type": "circle", "radius": 2 })

You can query the collection using the find method, but to simply list all the documents, use find() without a criteria specified.

> db.shapes.find()
{ "_id" : ObjectId("521a6743a8a1ce0d22037037"), "type" : "rectangle", "width" : 5, "height" : 7 }
{ "_id" : ObjectId("521a674aa8a1ce0d22037038"), "type" : "circle", "radius" : 2 }

To make a pretty output, chain pretty() on find().

> db.shapes.find().pretty()
{
  "_id" : ObjectId("521a6743a8a1ce0d22037037"),
  "type" : "rectangle",
  "width" : 5,
  "height" : 7
}
{
  "_id" : ObjectId("521a674aa8a1ce0d22037038"),
  "type" : "circle",
  "radius" : 2
}

Here is how to create an index, in this case on the radius attribute.

db.shapes.ensureIndex({ "radius": 1 })

To list all indexes.

> db.shapes.getIndexes()
[
  {
    "v" : 1,
    "key" : {
      "_id" : 1
    },
    "ns" : "mydb.shapes",
    "name" : "_id_"
  },
  {
    "v" : 1,
    "key" : {
      "type" : 1
    },
    "ns" : "mydb.shapes",
    "name" : "type_1"
  }
]

Droping the collection.

> db.shapes.drop()
true

Droping the database.

> db.dropDatabase()
{ "dropped" : "mydb", "ok" : 1 }

Exiting the shell.

> exit
bye

You can learn more about the MongoDB shell by reading the reference.