
Overview
The aim of this post is to list out commonly and sometimes rarely used MongoDB commands, queries and Aggregation framework. To install MongoDB community server, please follow
Setting Up MongoDB Community Server
You can also refer the MongoDB documentation for an enhanced info.
Commands
Show Databases
> show dbs admin 0.000GB config 0.000GB local 0.000GB
Create Database
use {database name}
eg:
> use universe switched to db universe
Create Collection
db.createCollection({planet_name})
> db.createCollection('planet') { "ok" : 1 }
Show Collections
show collections
> show collections planet
Drop Collection
db.{collection_name}.drop()
> db.planet.drop() true
Drop Database
db.dropDatabase()
> db.dropDatabase() { "dropped" : "universe", "ok" : 1 }
Insert a Document
db.{collection_name}.insert({document})
> db.planet.insert({ name: 'Mars', numberOfMoons: 2 }) WriteResult({ "nInserted" : 1 })
Query Document
db.{collection_name}.find()
> db.planet.find() { "_id" : ObjectId("5dc1415563b4683f19487261"), "name" : "Mars", "numberOfMoons" : 2 }
Query document with a field value
db.{collection_name}.find({query})
eg:
> db.planet.find({"name" : "Mars"}) { "_id" : ObjectId("5dc1415563b4683f19487261"), "name" : "Mars", "numberOfMoons" : 2 }
Update a Document
db.{collection_name}.update({criteria}, {update})
Eg:
> db.planet.updateOne( { name: "Mars" }, { $set: { "numberOfMoons": 3 } } ) { "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
Delete Document
db.{collection_name}.deleteOne(query)
Eg:
> db.planet.deleteOne({"name" : "Mars"}) { "acknowledged" : true, "deletedCount" : 1 }
Project field
db .{collection_name} .find( {query,} { projection } )
Eg:
> db.planet.find({}, { name: 1, numberOfMoons: 1, _id: 0 } ) { "name" : "Earth", "numberOfMoons" : 1 } { "name" : "Mars", "numberOfMoons" : 2 }
Create Single Index
> db.planet.createIndex( { name: 1 } ) { "createdCollectionAutomatically" : false, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }
Compound Index
> db.planet.createIndex( { name: 1, numberOfMoons: 1 } ) { "createdCollectionAutomatically" : false, "numIndexesBefore" : 2, "numIndexesAfter" : 3, "ok" : 1 }
Show all indexes
> db.planet.getIndexes()
Drop Index
Conclusion
I’ll like to keep this page as a quick reference and will keep on adding/updating commands.
Credits: Photo by Fernando Hernandez on Unsplash