MongoDb - deleting data in MongoDB

1. Methods for Deletion

MongoDB provides three main ways to delete data:

1. deleteOne(filter, options)
   → deletes the first matching document.

2. deleteMany(filter, options)
   → deletes all documents that match the filter.

3. db.collection.drop()
   → deletes the entire collection (all documents + metadata).

2. Examples

a) Delete One Document

db.users.deleteOne({ name: "Alice" })

• Removes the first document where name = "Alice".

b) Delete Multiple Documents

db.users.deleteMany({ age: { $lt: 25 } })

• Removes all users younger than 25.

c) Delete All Documents in a Collection

db.users.deleteMany({})

• Removes everything inside users collection, but keeps the collection itself.

d) Drop a Collection

db.users.drop()

• Completely removes the users collection (including indexes).

e) Drop a Database

db.dropDatabase()

• Deletes the entire current database and all its collections.

3. Return Value

Both deleteOne() and deleteMany() return a result object:

Example:

{ "acknowledged": true, "deletedCount": 3 }