MongoDB query to get distinct FirstName values from documents

For distinct values, use distinct(). Let us create a collection with documents −

> db.demo303.insertOne({FirstName:"Chris",LastName:"Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea0f6f8647eb59e56202f") } > db.demo303.insertOne({FirstName:"John",LastName:"Doe"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea104f8647eb59e562030") } > db.demo303.insertOne({FirstName:"Chris",LastName:"Smith"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea10df8647eb59e562031") } > db.demo303.insertOne({FirstName:"John",LastName:"Smith"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea121f8647eb59e562032") } > db.demo303.insertOne({FirstName:"David",LastName:"Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e4ea136f8647eb59e562033") }

Display all documents from a collection with the help of find() method −

> db.demo303.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5e4ea0f6f8647eb59e56202f"),    "FirstName" : "Chris",    "LastName" : "Brown" } {    "_id" : ObjectId("5e4ea104f8647eb59e562030"),    "FirstName" : "John",    "LastName" : "Doe" } {    "_id" : ObjectId("5e4ea10df8647eb59e562031"),    "FirstName" : "Chris",    "LastName" : "Smith" } {    "_id" : ObjectId("5e4ea121f8647eb59e562032"),    "FirstName" : "John",    "LastName" : "Smith" } {    "_id" : ObjectId("5e4ea136f8647eb59e562033"),    "FirstName" : "David",    "LastName" : "Miller" }

Following is the query to get the distinct FirstName values −

> db.demo303.distinct("FirstName");

This will produce the following output −

[ "Chris", "John", "David" ]