Free MongoDB C100DEV Exam Questions

Question 1

Consider a MongoDB database containing a collection of documents representing online orders for an e-commerce website. The documents have the following structure:

{

"_id": ObjectId("5f95a1d11a12b400001b75c0"),

"order_number": "ORD-001",

"order_date": ISODate("2022-01-01T00:00:00.000Z"),

"customer": {

"name": "John Doe",

"email": "johndoe@example.com"

},

"items": [

{ "product_name": "Smartphone", "quantity": 2, "price": 800 },

{ "product_name": "Laptop", "quantity": 1, "price": 1500 }

],

"shipping_address": {

"street": "123 Main St",

"city": "New York",

"state": "NY",

"zipcode": "10001"

},

"total_amount": 3000

}

Select an aggregation pipeline that returns the total sales amount by state and month, for orders placed in the year 2022. The result should have the following format:

A : [ { "$match": { "order_date": { "$gte": ISODate("2022-01-01T00:00:00.000Z"), "$lt": ISODate("2023-01-01T00:00:00.000Z") } } }, { "$group": { "_id": { "state": "$shipping_address.state", "month": { "$month": "$order_date" } }, "sales_amount": { "$sum": "$total_amount" } } }, { "$project": { "state": "$_id.state", "month": "$_id.month", "sales_amount": "$sales_amount", "_id": 0 } }]

B : [ { "$group": { "_id": { "state": "$shipping_address.state", "month": { "$month": "$order_date" } }, "sales_amount": { "$sum": "$total_amount" } } }, { "$project": { "state": "$_id.state", "month": "$_id.month", "sales_amount": "$sales_amount", "_id": 0 } }]

C : [ { "$match": { "order_date": { "$gte": ISODate("2022-01-01T00:00:00.000Z"), "$lt": ISODate("2023-01-01T00:00:00.000Z") } } }, { "$group": { "sales_amount": { "$sum": "$total_amount" } } }, { "$project": { "state": "$_id.state", "month": "$_id.month", "sales_amount": "$sales_amount", "_id": 0 } }]

D : [ { "$match": { "order_date": { "$gte": ISODate("2022-01-01T00:00:00.000Z"), "$lt": ISODate("2023-01-01T00:00:00.000Z") } } }, { "$project": { "state": "$_id.state", "month": "$_id.month", "sales_amount": "$sales_amount", "_id": 0 } }]

Answer: A

Question 2

Consider a MongoDB collection named orders which has documents in the following format:

{

"_id" : ObjectId("5f5b0d2f3e3dfbcc11c84444"),

"orderId" : 1001,

"customerId" : 200,

"items" : [

{

"productId" : 101,

"quantity" : 2

},

{

"productId" : 102,

"quantity" : 1

}

],

"totalAmount" : 250,

"status" : "Pending"

}

What is the correct syntax to find and update the first document in the orders collection where "status" is "Pending", and change the "status" field to "Completed" using the findAndModify method?

A : db.orders.findAndModify( { status: "Pending" }, { $set: { status: "Completed" } })

B : db.orders.findAndModify({ query: { status: "Pending" }, update: { $set: { status: "Completed" } }})

C : db.orders.findAndModify({ query: { status: "Pending" }, status: "Completed" })

D : db.orders.findAndModify({ status: "Pending" }, { status: "Completed" })

Answer: B

Question 3

In a MongoDB database with referenced relationships, what is the advantage of using a separate collection for each entity over using a single collection for all entities?

A : Improved maintainability and reduced complexity of updates to related entities.

B : Improved query performance and reduced complexity of updates to related entities.

C : Improved maintainability and increased scalability.

D : Improved query performance and increased scalability.

Answer: A

Question 4

You have a MongoDB collection named students, where each document represents a student. The documents include fields like name, age, and courses. The courses field is an array that lists the course codes each student is enrolled in. You want to find all students enrolled in the course with the code "CS101". Which query will correctly retrieve all students enrolled in "CS101"?

A : db.students.find({ "courses": { $elemMatch: { $eq: "CS101" } } })

B : db.students.find({ "courses": [ "CS101" ] })

C : db.students.find({ "courses": { $in: "CS101" } })

D : db.students.find({ "courses": "CS101" })

Answer: D

Question 5

Consider the following situation: You are a MongoDB Developer and are currently working on an application that requires complex reporting on large amounts of data. The application stores its data in MongoDB, which has grown significantly. To maintain efficiency and manageability, you decide to use MongoDB views. You want to create a view "UsersView" that includes only username, email, and createdAt fields from the Users collection. Which of the following commands would you use?

A : db.createView("UsersView", "Users", [{$project: {username: 1, email: 1, createdAt: 1}}])

B : db.Users.createView("UsersView", {$project: {username: 1, email: 1, createdAt: 1}})

C : db.Users.createView("UsersView", "Users", [{$project: {username: 1, email: 1, createdAt: 1}}])

D : db.Users.createView("UsersView", [{$project: {username: 1, email: 1, createdAt: 1}}])

Answer: A