2023-12-19

Learn MongoDB in 1 Hour

URL: https://www.youtube.com/watch?v=c2M-rlkkT5o

• Database is a set of collections
• Collection is a set of Documents
• Document is a set of Key-Value pairs that represent an object

Creating a DB

• use <dbName>

Creating a collection

db.createCollection()

Dropping a database

db.dropDatabase()

Inserting a single document to a collection

db.<collectionName>.insertOne(<JSON>)

Inserting multiple documents to a collection

db.<collectionName>.insertMany([<JSONs separated by comma>])

Querying all documents in a collection

db.<collection>.find()

Data types

• String
• Integer
• Double
• Boolean
• Date
• Null
• Array
• Document

Sorting documents

db.<collection>.find().sort({}) The arg to sort is a document The keys are keys to sort the documents by and the value belongs to 1 or -1. 1 mean ascending and -1 means descending

Limiting documents

db.<collection>.find().limit(n: number) n is the number of documents to return. By default the are sorted by_id

Find documents

db.<collection>.find({query}, {projection}) query is a document projection is a document that has keys to boolean values indicating if that key is to be returned as a result

Updating a single document

db.<collection>.updateOne({filter}, {update}) update is a document with keys that are atomic operators such as $set and $unset

Set a field if that field doesn’t exist

db.<collection>.updateMany({field:{$exists:false}}, {field: defaultVal})