# MongoDB

• Getting Started
• Insert commands
• Find commands
  • Sorting results
• Delete commands
• Update commands
• Aggregation commands

# Getting Started

Command	Description
mongo	Start the MongoDB shell.
mongod	Start the MongoDB server.
db	Show the current database.
show dbs	List all available databases.
use <database>	Switch to a specific database.
show collections	List all collections in the current database.

# Insert commands

Command	Description
db.collectionName.insert()	Insert a document into a collection.
db.collectionName.insertMany()	Insert many documents into a collection.

db.products.insertOne({ name: "Product 2", price: 19.99 })

db.products.insertMany([
    { name: "Product 1", description: "Description of Product 1.", price: 19.99, units: 50 },
    { name: "Product 2", description: "Description for Product 2.", price: 29.99, units: 30 },
    { name: "Product 3", description: "Description for Product 3.", price: 9.49, units: 100 },
])

# Find commands

Command	Description
db.collectionName.find().limit()	Limit the number of results in a query.
db.collectionName.find().skip()	Skip a specified number of results in a query.
db.collectionName.find().count()	Count the number of documents in a collection.
db.collectionName.find().distinct()	Find distinct values in a field.
db.collectionName.find().pretty()	Format query results for readability.
db.collectionName.find().explain()	Get query execution plan and statistics.
db.collectionName.find().forEach()	Iterate over query results and apply a function.
db.collectionName.find().mapReduce()	Perform map-reduce operations.
db.collectionName.find().hint()	Force MongoDB to use a specific index.

db.products.find() // all
db.products.find({field: value}) // filter
db.products.find({field: value}, { field: 1, otherField: 1 }) // filter and show fields

# Sorting results

db.collectionName.find().sort({ sortBy: 1 }) // ascending
db.collectionName.find().sort({ sortBy: -1 }) // descending
// sort by multiple fields
db.collectionName.find().sort({ sortBy: 1, anotherSortBy: 1 })
db.collectionName.find().sort({ sortBy: -1, anotherSortBy: 1 })

# Delete commands

Command	Description
db.collectionName.deleteOne()	Delete a single document from a collection.
db.collectionName.deleteMany()	Delete multiple documents from a collection.

db.products.deleteOne({ name: "Product 1"})
// delete all
db.products.deleteMany({})

# Update commands

db.products.updateOne({ name: "Product 1"}, { $set: { price: 29.99 }})

| db.collectionName.update() | Update documents in a collection. | | db.collectionName.remove() | Remove documents from a collection. | | db.collectionName.aggregate() | Perform aggregation operations on a collection. | | db.collectionName.createIndex() | Create an index on a collection field. | | db.collectionName.dropIndex() | Delete an index from a collection. |

# Aggregation commands

Command	Description
db.collectionName.aggregate().unwind()	Deconstruct an array field.
db.collectionName.aggregate().group()	Group documents by a specified field.
db.collectionName.aggregate().match()	Filter documents in an aggregation pipeline.
db.collectionName.aggregate().sort()	Sort documents in an aggregation pipeline.
db.collectionName.aggregate().project()	Include or exclude fields in an aggregation.
db.collectionName.aggregate().lookup()	Perform a left outer join with another collection.