Database and collection creation in MongoDB - Mini Project: Build & Apply

Create a MongoDB Database and Collection

📖 Scenario: You are setting up a new MongoDB database for a small bookstore. You need to create the database and a collection to store book information.

🎯 Goal: Create a MongoDB database called bookstore and a collection inside it called books.

📋 What You'll Learn

Create a database named bookstore

Create a collection named books inside the bookstore database

💡 Why This Matters

🌍 Real World

Creating databases and collections is the first step in organizing data for any application that uses MongoDB, such as inventory systems, content management, or user data storage.

💼 Career

Database administrators and backend developers often create and manage MongoDB databases and collections to store and retrieve application data efficiently.

1

Create the bookstore database

Switch to the MongoDB database named bookstore using the command use bookstore.

MongoDB

# Switch to the bookstore database
# Your code here

Hint

Use the use command to switch to the database.

2

Create the books collection

Create a collection named books in the bookstore database using db.createCollection('books').

MongoDB

use bookstore
# Create the books collection
# Your code here

Hint

Use db.createCollection('books') to create the collection.

3

Verify the collection creation

List all collections in the bookstore database using show collections to confirm books exists.

MongoDB

use bookstore
db.createCollection('books')
# List collections to verify
# Your code here

Hint

Use show collections to see all collections in the current database.

4

Insert a sample document into books

Insert a sample book document into the books collection using db.books.insertOne({ title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' }).

MongoDB

use bookstore
db.createCollection('books')
show collections
# Insert a sample book document
# Your code here

Hint

Use db.books.insertOne() to add a document to the collection.

Practice

1. What does the command use myDatabase do in MongoDB?

easy

A. It deletes the database named 'myDatabase'.

B. It creates a collection named 'myDatabase'.

C. It switches to the database named 'myDatabase' or creates it if it doesn't exist.

D. It lists all collections in the current database.

Solution

1. Step 1: Understand the use command

   The use command in MongoDB switches the current database context to the specified database.

2. Step 2: Behavior when database does not exist

   If the specified database does not exist, MongoDB creates it when you first store data in it.

3. Final Answer:

   It switches to the database named 'myDatabase' or creates it if it doesn't exist. -> Option C

4. Quick Check:

   use databaseName switches or creates database [OK]

Hint: Remember: use switches or creates database [OK]

Common Mistakes:

• Thinking use creates collections
• Confusing database and collection commands
• Assuming use deletes databases

2. Which of the following is the correct syntax to create a new collection named users in the current database?

easy

A. db.createCollection('users')

B. create collection users

C. db.users.create()

D. use users

Solution

1. Step 1: Identify the MongoDB command for collection creation

   The correct MongoDB command to create a collection is db.createCollection('collectionName').

2. Step 2: Match the syntax with the options

   db.createCollection('users') matches the correct syntax exactly for creating a collection named 'users'.

3. Final Answer:

   db.createCollection('users') -> Option A

4. Quick Check:

   Use db.createCollection('name') to create collections [OK]

Hint: Use db.createCollection('name') to create collections [OK]

Common Mistakes:

• Using SQL-like syntax such as 'create collection users'
• Trying to create collection with db.users.create()
• Using use users to create collection

3. What will be the result of running these commands in order?

use shopDB
db.createCollection('products')
db.getCollectionNames()

medium

A. Error: createCollection not found

B. ['shopDB']

C. []

D. ['products']

Solution

1. Step 1: Switch to or create the database 'shopDB'

   The use shopDB command switches to the database named 'shopDB'. If it doesn't exist, it will be created when data is added.

2. Step 2: Create a collection named 'products'

   The command db.createCollection('products') creates a new collection called 'products' inside 'shopDB'.

3. Step 3: List collections in the current database

   db.getCollectionNames() returns an array of collection names in the current database. Since 'products' was created, it returns ['products'].

4. Final Answer:

   ['products'] -> Option D

5. Quick Check:

   Created collection appears in db.getCollectionNames() [OK]

Hint: Created collections appear in db.getCollectionNames() [OK]

Common Mistakes:

• Expecting database name in collection list
• Assuming collections list is empty after creation
• Confusing collection names with database names

4. Identify the error in this MongoDB command sequence:

use testDB
db.createCollection(users)

medium

A. Missing quotes around collection name 'users'.

B. The use command is incorrect.

C. The collection name cannot be 'users'.

D. The command createCollection does not exist.

Solution

1. Step 1: Check syntax of createCollection command

   The collection name must be a string, so it requires quotes around it.

2. Step 2: Identify the error in the command

   The command db.createCollection(users) is missing quotes around 'users', causing a syntax error.

3. Final Answer:

   Missing quotes around collection name 'users'. -> Option A

4. Quick Check:

   Collection names must be strings in quotes [OK]

Hint: Always put collection names in quotes in createCollection [OK]

Common Mistakes:

• Omitting quotes around collection names
• Misusing use command syntax
• Thinking collection names cannot be common words

5. You want to create a new database called libraryDB and inside it a collection named books. Which sequence of commands will achieve this correctly?

hard

A. create database libraryDB
create collection books

B. use libraryDB
db.createCollection('books')

C. use books
db.createCollection('libraryDB')

D. db.createCollection('libraryDB.books')

Solution

1. Step 1: Switch to or create the database 'libraryDB'

   The command use libraryDB switches to the database named 'libraryDB'. If it doesn't exist, it will be created when data is added.

2. Step 2: Create the collection 'books' inside 'libraryDB'

   Using db.createCollection('books') creates the collection named 'books' in the current database context.

3. Final Answer:

   use libraryDB db.createCollection('books') -> Option B

4. Quick Check:

   Switch database then create collection [OK]

Hint: Switch database first, then create collection inside it [OK]

Common Mistakes:

• Trying to create database and collection in one command
• Using SQL syntax like 'create database'
• Confusing collection and database names