Free MongoDB C100DEV Exam Questions

Question 1

Consider the following documents in a MongoDB collection orders:

{

"_id": 1,

"customer_id": 101,

"item": "apple",

"price": 0.5,

"quantity": 100,

"date": ISODate("2022-01-01T00:00:00Z")

},

{

"_id": 2,

"customer_id": 102,

"item": "banana",

"price": 0.25,

"quantity": 50,

"date": ISODate("2022-01-02T00:00:00Z")

},

{

"_id": 3,

"customer_id": 101,

"item": "orange",

"price": 0.75,

"quantity": 75,

"date": ISODate("2022-01-03T00:00:00Z")

}

What is the aggregation pipeline to group the documents by "customer_id" and calculate the sum of the "quantity" field for each group, sorted in descending order by the sum of the "quantity" field?

A : db.runCommand({ aggregate: "orders", group: { _id: "$customer_id", total_quantity: { $sum: "$quantity" } }, sort: { total_quantity: -1 }})

B : db.orders.aggregate([ { $group: { _id: "$customer_id", total_quantity: { $sum: "$quantity" } } }, { $sort: { total_quantity: 1 } }])

C : db.orders.aggregate([ { $groupBy: { customer_id: "$customer_id" }, total_quantity: { $sum: "$quantity" } }, { $sort: { total_quantity: 1 } }])

D : db.orders.aggregate([ { $group: { _id: "$customer_id", total_quantity: { $sum: "$quantity" } } }, { $sort: { total_quantity: -1 } }])

Answer: D

Question 2

In your database there is a collection named companies with the following document structure:

{

name: 'Wize',

relationships: [

{

is_past: false,

title: 'Head of Product',

person: {

first_name: 'Ethan',

last_name: 'Smith',

permalink: 'ethan-smith'

}

},

{

is_past: true,

title: 'Director, Business Development',

person: {

first_name: 'Stephanie',

last_name: 'Quay',

permalink: 'stephanie-quay'

}

},

{

is_past: true,

title: 'Sr. Engineer',

person: {

first_name: 'Stefan',

last_name: 'Antonowicz',

permalink: 'stefan-antonowicz'

}

]

}

Which of the following queries should you use to extract all companies that have "Co-Founder" title in relationships field (Array)?

A : db.companies.find( { relationships: { $expr: { title: 'Co-Founder' } } } )

B : db.companies.find( { relationships: { $elemMatch: { title: 'Co-Founder' } } } )

C : db.companies.find( { relationships: { $match: { title: 'Co-Founder' } } } )

D : db.companies.find( { relationships: { $eq: { title: 'Co-Founder' } } } )

Answer: B

Question 3

In MongoDB, the $out operator is commonly used within an aggregation pipeline. Which of the following statements accurately describes the functionality and usage of the $out operator?

A : $out operator is used to output the results to a specified collection.

B : $out operator can be used to output the results to a collection in a different MongoDB database.

C : $out operator is used to export data directly to a file.

D : $out operator is used to read data from multiple collections in a single command.

Answer: A

Question 4

Which of the following statements correctly describes the relationship between BSON and JSON in MongoDB?

A : BSON and JSON are exactly the same data format, and the terms can be used interchangeably.

B : MongoDB uses JSON for data storage, and BSON is only used for querying data.

C : BSON is a binary representation of JSON-like documents, with additional data types not found in JSON.

D : BSON is a subset of JSON and only includes a portion of JSON's data types.

Answer: C

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?

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