MongoDB: Delete Documents in a Collection

MongoDB provides the following methods to delete one or more documents in a collection.

• db.collection.deleteOne() - Deletes the first matching document in a collection.
• db.collection.deleteMany() - Deletes all the matching documents in a collection.

db.collection.deleteOne()

Use the db.<collection>.deleteOne() method to delete the first documents that match with the specified filter criteria in a collection.

Syntax:

db.collection.deleteOne(filter, options)

Parameters:

1. filter: The selection criteria for the update, same as find() method.
2. options: Optional. May contains options for update behavior. It includes writeConcern, collation, and hint parameters.

In the above syntax, db points to the current database, <collection> points is an existing collection name.

To demonstrate the delete operation, insert the following sample documents in the employees collection.

db.employees.insertMany([
    { 
        _id:1,
        firstName: "John",
        lastName: "King",
        email: "[email protected]",
        salary: 5000
    },
    { 
        _id:2,
        firstName: "Sachin",
        lastName: "T",
        email: "[email protected]",
        salary: 8000
    },
    { 
        _id:3,
        firstName: "James",
        lastName: "Bond",
        email: "[email protected]",
        salary: 7500
    },
    { 
        _id:4,
        firstName: "Steve",
        lastName: "J",
        email: "[email protected]",
        salary: 7000
    },
    { 
        _id:5,
        firstName: "Kapil",
        lastName: "D",
        email: "[email protected]",
        salary: 4500
    },
    { 
        _id:6,
        firstName: "Amitabh",
        lastName: "B",
        email: "[email protected]",
        salary: 7000
    }
])

The following deletes a document from the employees collection.

db.employees.deleteOne({ salary:7000 }) 

{ acknowledged: true, deletedCount: 1 }

The above command deletes the first matching document even if multiple documents match with the specified criteria.

deleteMany()

Use the db.<collection>.deleteMany() method to delete all the documents that match with the specified filter criteria in a collection.

Syntax:

db.collection.deleteMany(filter, options)

Parameters:

1. filter: The selection criteria for the update, same as find() method.
2. options: Optional. May contains options for update behavior. It includes writeConcern and collation, and hint parameters.

The following deletes all documents from the employees collection that match with the specified criteria.

db.employees.deleteMany({ salary:7000 }) 

{ acknowledged: true, deletedCount: 2 }

The following deletes all documents where salary is less than 7000.

db.employees.deleteMany({ salary: { $lt:7000} }) 

{ acknowledged: true, deletedCount: 2 }

If you specify an empty criteria then it will delete all documents in a collection.

db.employees.deleteMany({ }) //deletes all documents 

{ acknowledged: true, deletedCount: 6 }