Trusted answers to developer questions
Trusted Answers to Developer Questions

Related Tags

mongodb
commands
communitycreator

12 basic MongoDB commands

Theodore Kelechukwu Onyejiaku

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

What is MongoDB Database?

MongoDB is a source-available, cross-platform, document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. (Wikipedia)

MongoDB is not an SQL-based database. In MongoDB, tables are referred to as Collections, and Records are referred to as Documents.

12 MongoDB commands you should know

Below, we discuss some useful MongoDB shell commands.

1. How to show the databases present

  • show dbs

2. How to create a database

  • use [name of database]

Example

use users

3. How to check active collection or database

  • db

4. How to create a collection

  • db.createCollection("[name of collection]")

Example

db.createCollection("customer")

5. How to show collections

  • show collections

6. How to insert a document into a collection

  • db.[name of collection].insert({})

Example

db.customer.insert({"name": "Theodore", "gender": "M"})

Or, put the documents in an array to insert more than one document:

db.customer.insert([
    {"name": "Theodore", "gender": "M"},
    {"name": "Jane Doe", "gender": "F"},
    {"name", "John Doe", "gender": "M"}
])

7. How to show all documents in a collection

  • db.[collection Name].find()

or

  • db.[collection name].find().pretty() for a well indented list.

Example

db.customer.find().pretty()

8. How to limit fields when listing all the documents present in a collection

Example

db.customer.find({},{id:1}).pretty()

The above will only display _id the result.

9. How to update a document with $set

  • db.[name of collection].update({},{$set: {}})

Example

db.customer.update(
    {"name":"Theodore"}, 
    {$set: 
        {"name": "Theodore Kelechukwu Onyejiaku"}
    }
)

10. How to rename a field in a document with $rename

Example

db.customer.update(
    {"name": "Theodore Kelechukwu Onyejiaku"},
    {$rename: 
        {"gender":"sex"}
    }
)

11. How to delete or remove a field with $unset

Example

db.customer.update(
    {"name": "Theodore Kelechukwu Onyejiaku"},
    {$unset: 
        {"sex": 1}
    }
)

12. How to remove a document from a collection

  • db.[name of collections].remove({})

or

  • db.[name of collections].remove({}, {justOne: true}) to remove just one with the unique match.

Example

db.customer.remove({"name":"Jane Doe"})

Conclusion

We have gone over some of the basic and most frequently used MongoDB commands. Feel free to try them out, and of course, find some more advanced commands. Happy shelling!

RELATED TAGS

mongodb
commands
communitycreator

CONTRIBUTOR

Theodore Kelechukwu Onyejiaku

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

Keep Exploring