Creating Database In MongoDB


A Database holds multiple collections of documents in MongoDB and MongoDB holds multiple databases.

>_ Command To Create a Database

MongoDB doesn’t provide any command to create Database, it has a command named use to switch or select the database with the following syntax.

use <databasename>

MongoDB will switch the current database to the provided one if exist else it will create a database with that name.
Means for example I am using the use command as
use TutorialToUs
If the TutorialToUs is already exist then MongoDB selects the current database as ‘TutorialToUs’if there is no database with that name then it will createsandswitches to created ‘TutorialToUs;
Note:-
1. MongoDB will create the database only if that database have minimum a single collection.

Means after usage of use command it will creates db and while leaving from this db(at the time of switching to other db or exit from mongo) if the database doesn’t have a collection then automatically it will be vanished.

>_ Command to list Databases

Syntax:-

show dbs

This command will return the databasenames and its storage size. Example:-

show dbs

Sample Output:-

local	0.001GB 
test    0.061GB 

Note:-

1. MongoDB will vanish if the DB doesn’t have any collection after using use command. For that see these example

stepno cmd output
1 show dbs local 0.001GB
test 0.061GB
2 use TutorialToUs switched to db TutorialToUs
3 show dbs local 0.001GB
test 0.061GB
4 db.users.insert({name:”Alex”}) Inserted 1 record(s) in 2ms
5 show dbs local 0.001GB
test 0.061GB
TutorialToUs 0.000GB

!!Note:-

In the above after step2 ‘TutorialToUs’ created only after step4 means after creating a collection for that DB.

>_ Command to View the Current Database

Syntax:-

								 db 

it will echo the current database name.