Question 1

Consider the following scenario: You have a MongoDB collection named users that stores user information. Each document in the collection has the following structure:

{

"_id": ObjectId("609fe4b5728ad805aef1a88d"),

"name": "John Doe",

"age": 30,

"email": "[email protected]",

"address": {

"street": "123 Main St",

"city": "New York",

"state": "NY",

"zipcode": "10001"

}

You need to retrieve all the documents from the users collection and convert them to an array format. Which of the following MongoDB queries should you use for this task?

Options :

A : db.users.find().convertToArray()

B : db.users.find().toArray()

C : db.users.toArray()

D : db.users.aggregate({ $toArray: "users" })

Answer: B

Question 2

In MongoDB, which statement accurately describes a typical task for a MongoDB developer related to schema validation?

Options :

A : Schema validation enables the creation of complex relationships between multiple collections.

B : Schema validation guarantees the uniqueness of a specific field across all documents in a collection.

C : Schema validation ensures the presence of required fields and their data types within a document.

D : Schema validation provides real-time data synchronization across multiple MongoDB instances.

Answer: C

Question 3

Given the following documents in a collection:

{ _id: 1, n: [1,2,5], p: 0.75, c: 'Green' },

{ _id: 2, n: 'Orange', p: 'Blue', c: 42, q: 14 },

{ _id: 3, n: [1,3,7], p: 0.85, c: 'Orange' }

Which two documents can successfully be added in the same collection? (Select two)

Options :

A : { _id: 1, n: [1,2,5], p: 0.75, c: 'Green' }

B : { _id: 2, n: [1,2,5], p: 0.75, c: 'Green' }

C : { _id: 6, n: [1,3,7], p: 0.85, c: 'Orange }

D : { _id: 5, n: [1,2,5], p: 0.75, c: 'Green' }

Answer: C,D

Question 4

You have two collections in your MongoDB database: students and grades. The students collection contains the following document:

{

"_id": ObjectId("64d5b0e5c9d95a76ac3ebed2"),

"student_id": 1,

"name": "Alice"

}

The grades collection contains the following documents:

{

"_id": ObjectId("64d5b0e5c9d95a76ac3ebed3"),

"student_id": 2,

"course": "Math",

"grade": "A"

},

{

"_id": ObjectId("64d5b0e5c9d95a76ac3ebed4"),

"student_id": 2,

"course": "Science",

"grade": "B"

}

You run the following aggregation query to retrieve students along with their grades:

db.students.aggregate([

{

$lookup: {

from: "grades",

localField: "student_id",

foreignField: "student_id",

as: "grades_details"

}

])

What will be the structure of the documents returned by this aggregation query for the student with student_id: 1?

Options :

A :

{
    "_id": ObjectId("64d5b0e5c9d95a76ac3ebed2"),
    "student_id": 1,
    "name": "Alice",
    "grades_details": null
}

B :

{
    "_id": ObjectId("64d5b0e5c9d95a76ac3ebed2"),
    "student_id": 1,
    "name": "Alice",
    "grades_details": []
}

C :

{
    "_id": ObjectId("64d5b0e5c9d95a76ac3ebed2"),
    "student_id": 1,
    "name": "Alice",
    "grades_details": [
        {
            "course": "Math",
            "grade": "A"
        }
    ]
}

D :

{
    "_id": ObjectId("64d5b0e5c9d95a76ac3ebed2"),
    "student_id": 1,
    "name": "Alice",
    "grades_details": [
        {
            "course": "Math",
            "grade": "A"
        },
        {
            "course": "Science",
            "grade": "B"
        }
    ]
}

Answer: B

Question 5

You are working on a MongoDB database for a library system. The system tracks book information in a Books collection. A typical document in this collection looks like this:

Original Document:

{

"_id": ObjectId("book_id"),

"title": "The Art of Computer Programming",

"author": "Donald Knuth",

"genres": ["Computer Science", "Algorithms"],

"published_year": 1968,

"copies_available": 3

}

You are asked to update the document by replacing it with the following document:

Updated Document:

{

"title": "The Art of Computer Programming",

"published_year": 1973

}

After this update, what will the final document in the database look like?

Options :

A :

{
  "_id": ObjectId("book_id"),
  "title": "The Art of Computer Programming",
  "published_year": 1973
}

B :

{
  "_id": ObjectId("book_id"),
  "title": "The Art of Computer Programming",
  "author": "Donald Knuth",
  "genres": ["Computer Science", "Algorithms"],
  "published_year": 1973,
  "copies_available": 3
}

C :

{
  "title": "The Art of Computer Programming",
  "published_year": 1973,
  "author": "Donald Knuth"
}

D :

{
  "_id": ObjectId("book_id"),
  "title": "The Art of Computer Programming",
  "published_year": 1973,
  "genres": ["Computer Science"]
}

Answer: A