Getting Started with MongoDB

This article mainly introduces MongoDB basic commands, prerequisites, your local already installed MONGO.

First, the use of BASIC commands

　　1. Create a database

Command: Use

Use database_name: The user creates the database, if it exists, uses the database, and no is created.

Example: Creating a Database MyDB

>use MyDB

>switched to DB MyPort

　　2. Querying the currently selected database

Command: DB

　　3. Querying the Database list

Command: Show DB

Note: To display the database, you need to insert it into at least one file

　4. Deleting a database

Command: Db.dropdatabase ()

Note: Delete the database that is in use, or delete the default test database if there is no selection

　　5. Create a Collection

Command: Db.createcollection (name, options)

Parameters	Type	Describe
Name	String	The name of the collection to create
Options	Document	Optionally, specify the memory size and index options

Field	type	Description
Capped	Boolean	(optional) If true, the CAP collection is enabled. A capped collection is a fixed-size collection that automatically overwrites the oldest entry when it reaches its maximum size. If True is specified, the dimension parameter needs to be specified as well.
Autoindexid	Boolean	(optional) If true, the default value for the auto-create index _id field is false.
Size	Number	Optionally, specify a maximum size byte capping set. If the cap is true, then you also need to specify this field.
Max	Number	Optionally, specify the maximum number of files allowed in the capping collection.

Example:

>db.createcollection ("mycollection")

{"OK": 1}

> db.createcollection ("MyCol", {capped:true, autoindexid:true, size:6142800, max:10000})

{"OK": 1}

　　

　　In MongoDB, you do not need to create a collection. When inserting some files MongoDB automatically creates the collection.

Example:

　　　　

　

　　

Getting Started with MongoDB