MongoDB is a popular database that stores data JSON-like documents.
It offering high performance, scalability, and easy of use for modern application development.

1. find()- 

db.abc.find()

Find all documents in the "abc" collection

db.abc.find({ age: { $gt: 30 } })

Find documents where collection age is greater than 30.

2.findOne()-

db.abc.findOne()

Find the first document in the "abc" collection

3. insertOne()-

db.abc.insertOne({ username: "Tutorials_on_web", email: "info@tutorialsonweb.com", age: 25 })

Insert a new document into the "abc" collection

4. insertMany(): 

db.abc.insertMany([
  { username: "mahendra", email: "mahendra@tutorialsonweb.com", age: 30 },
  { username: "lokendra", email: "lokendra@tutorialsonweb.com", age: 35 }
])

Insert multiple documents into the "abc" collection.

5. updateOne()-

db.abc.updateOne({ username: "tutorials_on_web" }, { $set: { age: 31 } })

Update a document in the "abc" collection set age 31 where username is “tutorials_on_web”

6. updateMany()-

db.abc.updateMany({ status: "inactive" }, { $set: { status: "active" } })

Update multiple documents in the "abc" collection which records status is inactive.

7. deleteOne()-

db.abc.deleteOne({ username: "tutorials_on_web" })

Delete a document from the "abc" collection where username is tutorials_on_web

8. deleteMany()-

db.abc.deleteMany({ age: { $gte: 40 } })

Delete multiple documents from the "abc" collection where age is grater then 40.