Before starting run the commands brew doctor and then brew update
Unix Users please install using the docs
$ brew install mongodb
Once brew is done installing, take note of the Caveats section that is printed to your console. Just like what we did previously for postgres it might be best to create a symlink then two aliases to start and stop the mongo progress.
- Start your mongodb service
- Connect to your mongodb server with the command
$ mongo - Enter the command:
$ use local
Your prompt should look something like this:
MongoDB shell version: 3.0.4
connecting to: test
>
Enter 1 + 1, you'll notice that the mongodb-cli will evaluate to 2. This means that you are in MongoShell (a Javascript REPL). To further illustrate this go ahead and declare a new variable named person which is an object literal with a single property of name and set it to your name. Enter the command person to recall your object that you just created. You can do FOR loops and even declare and call functions.
$ help will show a menu of help commands.
- In a SQL database we have to create a database we have to run a query that looks like this:
CREATE DATABASE DB_NAME_HERE;- In MongoDB we can issue the
usecommand with the databse name as its only parameter.
To create a Database named mongodb_intro, to create it we will run this command $ use mongodb_intro. Now we are using a database, we can use db methods. To see what methods are available you can refer to the help command: $ db.help();
Forget what database you're using? $ db.getName();
- In a SQL database we have Tables but in MongoDB we have Collections.
- In a SQL database, Tables contain Rows of data. In MongoDB Collections contain Documents.
When we run the command $ db.getCollectionNames(); you should see an array with just one element in it, [ "system.indexes" ] this is used by MonoDB internally, besides that we don't have our own collection so lets create a collection named users... there are two ways to do it. Let's do both.
Creating a collection explicitly and inserting our person object (#1)
// create collection
$ db.createCollection("users"); //-> { "ok" : 1 }
// insert our data by calling db.collectionName.insert method
$ db.users.insert(person); //-> WriteResult({ "nInserted" : 1 })
// Query the database for Documents
$ db.users.find(); //-> prints all documents found in the users collection, should only be one objectbefore we continue we will need to drop the users collection
$ db.users.drop(); //-> true
Creating a collection implicityly by inserting data (#2)
$ db.users.insert(person); //-> WriteResult({ "nInserted" : 1 })
$ db.users.find(); //-> prints all documents found in the users collection, should only be one objectDo you see a difference between the two series of operations? Step #2 doesn't have a command that explicitly creates a collection yet a collection of users was created anyway. Also, you may have noticed that we haven't defined any Columns nor specified Data Types for these non-present columns. Crazy right? Basically MongoDB just takes a Javascript object, you tell it where you want to store it (Collection) and Mongo says, "Got the Data and I got the Collection to store it to, Thanks!".
MongoDB is very relaxed compared to SQL Databases.
Take some time to create another object to save to the users collections and instead of a name property, make up a few properties and then insert it into the collection then query your collection for the data.
Like Honey Badger, MongoDB don't care
- Can you find the
db.collectionMethod for Modifying a document that already exists? - Does MongoDB have aggregate methods?
- How is "Indexing" done in MongoDB
- What is "Sharding"?
- Does Mongo provide a way to migrate your data across multiple servers?