MongoDB installation Ubuntu
If you are using Unbuntu, the following link is an excellent reference:
https://www.digitalocean.com/community/tutorials/como-instalar-o-mongodb-no-ubuntu-16-04-pt
MongoDB installation procedures for MacOS-X
With homebrew installed, run $ brew install mongodb.
Install brew services with $ brew tap homebrew/services. Homebrew services allow you to easily add services like MongoDB to startup.
Run the command brew services start mongodb
Visit http://localhost:27017 to verify installation. If MongoDB has been installed correctly you will see the message It looks like you are trying to access MongoDB over HTTP on the native driver port. at the top of the browser window.
For Linux, consult the install guide at http://docs.mongodb.org/manual/administration/install-on-linux/. If you are using Windows, please see the Windows install guide at: http://docs.mongodb.org/manual/tutorial/install-mongodb-on-windows/.
MongoDB dir macosx
The databases are stored in the /usr/local/var/mongodb/ directory
The mongod.conf file is here: /usr/local/etc/mongod.conf
The mongo logs can be found at /usr/local/var/log/mongodb/
The mongo binaries are here: /usr/local/Cellar/mongodb/[version]/bin
To start mongodb server
$ sudo mongod --config /usr/local/etc/mongod.conf
To check current installed version
Check to see if any mongo service is running
$ launchctl list | grep mongo
If you have installed mongodb through homebrew then you can simply start mongodb through
$ brew services start mongodb
Then access the shell by
You can shut down your db by
$ brew services stop mongodb
For more options
MongoDB shell commands
Basic commands
| To do this |
Run this command |
Example |
| Connect to local host on default port 27017 |
mongo |
mongo |
| Connect to remote host on specified port |
mongo –host --port |
mongo –host 10.121.65.23 –port 23020 |
| Connect to a database |
mongo / |
mongo 10.121.65.58/mydb |
| Show current database |
db |
db |
| Select or switch database |
use |
use mydb |
| Execute a JavaScript file |
load() |
load (myscript.js) |
| Display help |
help |
help |
| Display help on DB methods |
db.help() |
db.help() |
| Display help on Collection |
db.mycol.help() |
db.mycol.help() |
Show commands
| To do this |
Run this command |
Example |
| Show all databases |
show dbs |
show dbs |
| Show all collections in current database |
show collections |
show collections |
| Show all users on current database |
show users |
show users |
| Show all roles on current database |
show roles |
show roles |
CRUD Operations
| To do this |
Run this command |
Example |
| Insert a new document in a collection |
db.collection.insert( ) |
db.books.insert({“isbn”: 9780060859749, “title”: “After Alice: A Novel”, “author”: “Gregory Maguire”, “category”: “Fiction”, “year”:2016}) |
| Insert multiple documents into a collection |
db.collection.insertMany([ , , ... ]) |
db.books.insertMany( [{“isbn”: 9780198321668, “title”: “Romeo and Juliet”, “author”: “William Shakespeare”, “category”: “Tragedy”, “year”: 2008}, {“isbn”: 9781505297409, “title”: “Treasure Island”, “author”: “Robert Louis Stevenson”, “category”: “Fiction”, “year”:2014}]) |
| Show all documents in the collection |
db.collection.find() |
db.books.find() |
| Filter documents by field value condition |
db.collection.find() |
db.books.find({“title”:”Treasure Island”}) |
| Show only some fields of matching documents |
db.collection.find(, ) |
db.books.find({“title”:”Treasure Island”}, {title:true, category:true, _id:false}) |
| Show the first document that matches the query condition |
db.collection.findOne(, ) db.books.findOne({}, {_id:false}) |
|
| Update specific fields of a single document that match the query condition |
db.collection.update(, ) |
db.books.update({title : “Treasure Island”}, {$set : {category :”Adventure Fiction”}}) |
| Remove certain fields of a single document the query condition |
db.collection.update(, ) |
db.books.update({title : “Treasure Island”}, {$unset : {category:””}}) |
| Remove certain fields of all documents that match the query condition |
db.collection.update(, , {multi:true} ) |
db.books.update({category : “Fiction”}, {$unset : {category:””}}, {multi:true}) |
| Delete a single document that match the query condition |
db.collection.remove(, {justOne:true}) |
db.books.remove({title :”Treasure Island”}, {justOne:true}) |
| Delete all documents matching a query condition |
db.collection.remove() |
db.books.remove({“category” :”Fiction”}) |
| Delete all documents in a collection |
db.collection.remove({}) |
db.books.remove({}) |
Indexing
| To do this |
Run this command |
Example |
| Create an index |
db.collection.createIndex({indexField:type}) Type 1 means ascending; -1 means descending |
db.books.createIndex({title:1}) |
| Create a unique index |
db.collection.createIndex({indexField:type}, {unique:true} ) |
db.books.createIndex({isbn:1},{unique:true}) |
| Create a index on multiple fields (compound index) |
db.collection.createIndex({indexField1:type1, indexField2:type2, …}) |
db.books.createIndex({title:1, author:-1}) |
| Show all indexes in a collection |
db.collection.getIndexes() |
db.books.getIndexes() |
| Drop an index |
db.collection.dropIndex({indexField:type}) |
db.books.dropIndex({author:-1}) |
| Show index statistics |
db.collection.stats() |
db.books.stats() |
Cursor methods
| To do this |
Run this command |
Example |
| Show number of documents in the collection |
cursor.count() |
db.books.find().count() |
| Limit the number of documents to return |
cursor.limit() |
db.books.find().limit(2) |
| Return the result set after skipping the first n number of documents |
cursor.skip() |
db.books.find().skip(2) |
| Sort the documents in a result set in ascending or descending order of field values |
cursor.sort( <{field : value}> ) |
value = 1 for ascending, -1 for descending db.books.find().sort({title : 1}) |
| Display formatted (more readable) result |
cursor.pretty() |
db.books.find({}).pretty() |
Comparison operators
| To do this |
Run this command |
Example |
| equals to |
{: { $eq: }} |
db.books.find({year: {$eq: 2016}}) |
| less than |
{: { $lt: }} db.books.find({year: {$lt: 2010}}) |
|
| less than or equal to |
{: { $lte: }} |
db.books.find({year: {$lte: 2008}}) |
| greater than |
{: { $gt: }} |
db.books.find({year: {$gt: 2014}}) |
| greater than or equal to |
{: { $gte: }} |
db.books.find({year: {$gte: 2008}}) |
| not equal to |
{: { $ne: }} |
db.books.find({year: {$ne: 2008}}) |
| value in |
{: { $in: [ , , ... }} |
db.books.find({year: {$in: [2008, 2016]}}) |
| value not in |
{: { $nin: [ , , ... }} |
db.books.find({year: {$nin: [2008, 2016]}}) |
Logical operators
| To do this |
Run this command |
Example |
| OR |
{ $or: [, ,...]} |
db.books.find( { $or: [{year: {$lte: 2008}}, {year: {$eq: 2016}}]} ) |
| AND |
{ $and: [, ,...]} |
db.books.find( { $and: [{year: {$eq: 2008}}, {category: {$eq: “Fiction”}}]} ) |
| NOT |
{ $not: {}} |
db.books.find( {$not: {year: {$eq: 2016} }}) |
| NOR |
{ $nor: [, ,...]} |
db.books.find( { $nor: [{year: {$lte: 2008}}, {year: {$eq: 2016}}]} ) |
Element operators
| To do this |
Run this command |
Example |
| Match documents that contains that specified field |
{: {$exists:true}} |
db.books.find( {category: {$exists: true }}) |
| Match documents whose field value is of the specified BSON data type |
{: {$type:value}} |
db.books.find( {category: {$type: 2 }}) |
MongoDB vs SQL syntax
Terminology and Concepts
| MySQL |
MongoDB |
| Table |
Collection |
| Row |
Document |
| Column |
Field |
| Joins |
Embedded documents, linking |
Querying
https://docs.mongodb.com/manual/reference/sql-comparison/
MongoDB with rails
When you set up your initial Rails project make sure to skip active record.
$ rails new my_app --skip-active-record --skip-test --skip-system-test
Add mongoid and bson to the Gemfile
ps: the gem ‘bson_ext’ is no longer necessary
run mongoid installer