Creating a collection is an automatic task in MongoDB. This is a distinguished feature in MongoDB, where a collection is automatically created when when we insert some documents. However in MongoDB, we can also create a collection manually, using the command db.createCollection.
- Type the command use DATABASE_NAME in the command prompt to create a new database or to select the already created database with the respective name.
For Example: use Hellodb
- Type the command createCollection(name, options) in the command prompt to create a new collection manually.
- The name parameter is used to define the name of the collection to be created and thus the passed parameter should be a string type value.
- The option parameter is used to define the memory size and indexing of the collection and thus the passed parameter should be a document type value.
- While the parameter name is a mandatory parameter, the parameter option is an optional parameter while sending the command createCollection(name, options).
For Example: db.createCollection(“HELLO”)
- For automatic creation of the collection directly insert a document into a collection with the desired name using the Collection_Name.insert(Document_name) command.
For Example: db.HELLO.insert ({“name”: “welcome”})
- Type the command show collections in the command prompt to check the created collection.
- Type the command collection_name.find() in the command prompt to see the inserted document in a collection.
For Example: db.HELLO.find()
The Values to be passed in the option parameter of the command db.createCollection(name, options):
Capped:
It takes a Boolean value to enable the capped collection ( a fixed size collection ), with the specified size, if the entered boolean value is true.
AutoIndexID:
It takes a Boolean value to automatically create an index on ID field, if the entered boolean value is true.
Size Number:
It takes a numerical value to specify the maximum size in bytes for an enabled capped collection.
Max Number:
It takes a numerical value to specify the maximum number of documents allowed in an enabled capped collection.