DATABASE » NOSQL » MONGODB

Queries

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Database ​

CommandDescription
dbShow current database.
show dbsShow available databases.
use my_dbSwitch/create database.
db.dropDatabase()Drop current database.

Collection ​

CommandDescription
show collectionsShow collections (tables).
db.groups db.getCollection('groups')Access a collection (ex: groups).
db.groups.renameCollection('party')Rename collection.
db.groups.drop()Drop collection.

Select ​

js
db.groups.find({})                                           // All
db.groups.find({name: 'party1'})                             // Query
db.groups.find({name: 'party1'}, {type: 'party'})            // Query with AND
db.groups.find({$or: [{name: 'party1'}, {name: 'party2'}]})  // Query with OR
db.groups.count()                                            // Number of matches
db.groups.find(query).pretty()                               // Prettify

Insert ​

Automatically creates the collection if it does not exist.

js
db.groups.insertOne({'name': 'party1', 'type': 'party'})
db.groups.insertMany([
  {'name': 'party1', 'type': 'party'},
  {'name': 'party2', 'type': 'party'}
])

Update ​

js
db.groups.update({_id: 'f43nm39f'}, {$set: {'name': 'cool_party'}})
db.groups.update({_id: 'f43nm39f'}, {$set: {'member_count': NumberInt(2)}})
db.groups.update({_id: 'f43nm39f'}, {$set: {'settings.type': 'party'}})    // Embedded object
db.groups.update({_id: 'f43nm39f'}, {$set: {'members.0.name': 'leader'}})  // Array
db.groups.find({}).forEach(function(obj) {
  obj.id = NumberInt(obj.id);
  db.groups.save(obj);
})

Rename a field:

js
db.groups.updateMany({}, {$rename: {'type': 'category'}})

Remove a field from one or multiple matches:

js
db.groups.update({_id: 'f43nm39f'}, {$unset: {'member_count': ''}})               // One
db.groups.update({'name': 'wat'}, {$unset: {'member_count': ''}}, {multi: true})  // Multiple

Remove ​

js
db.groups.remove({_id: 'f43nm39f'})