> For the complete documentation index, see [llms.txt](https://gchandra.gitbook.io/big-data-and-tools-with-nosql/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gchandra.gitbook.io/big-data-and-tools-with-nosql/nosql/mongodb/mongodb-commands.md).

# MongoDB Commands

To display all databases

```
> show dbs
```

Open existing or New database

```
use dbname
```

How to create a new database? 

```
use newdb
```

Create a new collection

```
// create a collection

db.createCollection("myFirstCollection")

// collection with capped size

// The size: 2 means a limit of two megabytes, and max: 2 sets the maximum number of documents to two.

db.createCollection("mySecondCollection", {capped : true, size : 2, max : 2})
```

Display list of Collections

```
show collections
```

```
// drop database in MongoDB CE

db.dropDatabase()

```

```
// Drop database in MongoDB Atlas

use test;

db.runCommand({"dropDatabase":1})
```


---

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