MongoDB: Create Database

Before we store data as documents or work on them, we first need to create a database.

In MongoDB, a database consists of collections; a collection in turn is a grouping of documents. A collection can only exist within one database.

Now if you are using a Mac, open your terminal and start the Mongo Daemon first. 

				
					$ mongod

Next, open a new terminal and start the Mongo Shell. 

				
					$ mongo
mongod and mongo shell

If you are using Windows, go to the /bin directory and double-click on the Mongo Daemon mongod.exe. And in the same /bin directory, double-click on mongo.exe next. This is the Mongo Shell from where you will be entering commands.

Now there are a few default databases in MongoDB, like admin, config and local . We will list all the databases with the following command 

				
					$ show databases

or 

				
					$ show dbs

You will find the admin, config and local databases listed by default.

Now unlike in SQL, there is no straight-forward command as "CREATE DATABASE" to create a database in MongoDB. To create a database in MongoDB, we first need to switch to it using the use command, and later add at least one record (document) to a collection in it.

Suppose we intend to create a database called books. Switch to it first using the use command. 

				
					$ use books

The number of characters in a database name should be less than 64 characters.

Now the above use command does not merely create a database. If you run 

				
					$ show databases
mongodb default databases

you will find that your newly "created" books database is not in the list. You need to store at least one document in a collection.

We will create a new collection called comics and will insert the details of the following comic book as a document into it: Planet Comics, No. 55 published on July, 1948.

planet comics 55 Cover scan of Planet Comics, No. 55 by Joe Doolin, via Wikimedia Commons. Public Domain 
							
					$ db.comics.insert({ 
						no: 55,
						title: 'Planet Comics',
						year: 1948 
					})

Now if you list all databases again, 

				
					$ show dbs

you will find the new database books listed.