Why managed databases matter in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to connect to a MongoDB database using the correct method.

MongoDB

const client = new MongoClient([1]);

Drag options to blanks, or click blank then click option'

A"mongodb://localhost:27017"

B"localhost:27017"

C"ftp://localhost:27017"

D"http://localhost:27017"

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTP or FTP protocols instead of MongoDB protocol.

Omitting the protocol prefix entirely.

The connection string for MongoDB starts with mongodb://. This tells the client how to connect to the database.

2fill in blank

medium

Complete the code to select the database named 'shopDB'.

MongoDB

const db = client.[1]('shopDB');

Drag options to blanks, or click blank then click option'

Adatabase

Bdb

CuseDatabase

DgetDatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Using useDatabase which is not a method in the driver.

Using database which is not a method in the driver.

In MongoDB's Node.js driver, client.db('name') selects the database.

3fill in blank

hard

Fix the error in the code to insert a document into the 'products' collection.

MongoDB

await db.collection('products').[1]({ name: 'Pen', price: 1.5 });

Drag options to blanks, or click blank then click option'

AaddDocument

BinsertMany

Cinsert

DinsertOne

Attempts:

3 left

💡 Hint

Common Mistakes

Using insertMany when inserting a single document.

Using non-existent methods like addDocument or insert.

The correct method to insert a single document is insertOne. Other options are either incorrect or used for multiple documents.

4fill in blank

hard

Fill both blanks to find all documents in the 'orders' collection where the status is 'pending'.

MongoDB

const pendingOrders = await db.collection('orders').[1]([2]);

Drag options to blanks, or click blank then click option'

Afind

BfindOne

C{ status: 'pending' }

D{ status: 'complete' }

Attempts:

3 left

💡 Hint

Common Mistakes

Using findOne which returns only one document.

Using the wrong filter object.

To get all matching documents, use find with a filter object specifying { status: 'pending' }.

5fill in blank

hard

Fill all three blanks to update the price of the product named 'Notebook' to 3.0.

MongoDB

await db.collection([1]).updateOne([2], { [3]: { price: 3.0 } });

Drag options to blanks, or click blank then click option'

A'products'

B{ name: 'Notebook' }

C$set

D'orders'

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong collection name.

Using an incorrect filter object.

Forgetting to use the update operator like $set.

We update one document in the 'products' collection where the name is 'Notebook'. The update operator $set changes the price.

Practice

1. Why do managed databases matter for developers?

easy

A. They handle setup and maintenance so developers focus on the app

B. They require developers to manage backups manually

C. They limit the types of queries you can run

D. They only work with specific programming languages

Solution

1. Step 1: Understand the role of managed databases

   Managed databases automate setup, maintenance, and scaling tasks.

2. Step 2: Identify the benefit for developers

   This automation lets developers focus on building their app, not managing the database.

3. Final Answer:

   They handle setup and maintenance so developers focus on the app -> Option A

4. Quick Check:

   Managed DBs free developers from setup [OK]

Hint: Managed DBs automate setup and maintenance [OK]

Common Mistakes:

• Thinking developers must manage backups manually
• Believing managed DBs restrict query types
• Assuming they only support certain languages

2. Which of the following is the correct way to connect to a managed MongoDB database using a connection string?

easy

A. sql://username:password@host:port/database

B. http://username:password@host:port/database

C. ftp://username:password@host:port/database

D. mongodb://username:password@host:port/database

Solution

1. Step 1: Recall MongoDB connection string format

   MongoDB uses the mongodb:// protocol prefix for connections.

2. Step 2: Identify the correct option

   Only mongodb://username:password@host:port/database uses the correct mongodb:// prefix with username, password, host, port, and database.

3. Final Answer:

   mongodb://username:password@host:port/database -> Option D

4. Quick Check:

   MongoDB connection strings start with mongodb:// [OK]

Hint: MongoDB URLs start with mongodb:// [OK]

Common Mistakes:

• Using http:// or ftp:// instead of mongodb://
• Omitting username or password in the string
• Confusing port numbers or database names

3. Given a managed MongoDB collection users with documents: {name: 'Alice', age: 30}, {name: 'Bob', age: 25}, what will the query db.users.find({age: {$gt: 27}}) return?

medium

A. [{name: 'Alice', age: 30}]

B. [{name: 'Bob', age: 25}]

C. []

D. Syntax error

Solution

1. Step 1: Understand the query filter

   The query looks for documents where age is greater than 27.

2. Step 2: Check which documents match

   Alice has age 30 (greater than 27), Bob has 25 (not greater than 27).

3. Final Answer:

   [{name: 'Alice', age: 30}] -> Option A

4. Quick Check:

   age > 27 returns Alice only [OK]

Hint: Check which ages are greater than 27 [OK]

Common Mistakes:

• Including Bob who is 25 (not > 27)
• Expecting syntax error from valid query
• Returning empty array incorrectly

4. You wrote this code to insert a document into a managed MongoDB collection:

db.users.insert({name: 'Carol', age: 28})

But it throws an error. What is the likely fix?

medium

A. Add a semicolon at the end

B. Use insertMany instead

C. Change insert to insertOne

D. Remove the age field

Solution

1. Step 1: Identify deprecated method usage

   The insert method is deprecated in modern MongoDB drivers.

2. Step 2: Use the correct insertion method

   Use insertOne to insert a single document without error.

3. Final Answer:

   Change insert to insertOne -> Option C

4. Quick Check:

   Use insertOne for single document inserts [OK]

Hint: Use insertOne for single document inserts [OK]

Common Mistakes:

• Thinking semicolon fixes the error
• Using insertMany for one document unnecessarily
• Removing fields instead of fixing method

5. You want to ensure your managed MongoDB database automatically backs up data daily and scales during traffic spikes. Which feature of managed databases helps with this?

hard

A. Manual backup scheduling and fixed server size

B. Automated backups and auto-scaling

C. Only manual scaling with no backups

D. No backup or scaling features

Solution

1. Step 1: Identify backup and scaling needs

   You want daily backups and automatic scaling during traffic spikes.

2. Step 2: Match features of managed databases

   Managed databases provide automated backups and auto-scaling to meet these needs.

3. Final Answer:

   Automated backups and auto-scaling -> Option B

4. Quick Check:

   Managed DBs automate backups and scaling [OK]

Hint: Managed DBs automate backups and scaling [OK]

Common Mistakes:

• Assuming backups must be manual
• Thinking scaling is fixed and manual
• Believing managed DBs lack these features