Database and collection creation in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new database named 'school'.

MongoDB

use [1]

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

Alibrary

Bstore

Cschool

Doffice

Attempts:

3 left

💡 Hint

Common Mistakes

Using a database name other than 'school'.

Forgetting to use the 'use' command.

The use command switches to or creates the database named 'school'.

2fill in blank

medium

Complete the code to create a collection named 'students' in the current database.

MongoDB

db.[1].insertOne({name: 'Alice', age: 20})

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

Astudents

Bcourses

Cteachers

Dclasses

Attempts:

3 left

💡 Hint

Common Mistakes

Using a collection name other than 'students'.

Trying to create a collection without inserting a document.

In MongoDB, inserting a document into a collection creates the collection if it does not exist. Here, 'students' is the collection name.

3fill in blank

hard

Fix the error in the code to create a collection named 'books'.

MongoDB

db.createCollection('[1]')

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

Abooks

BbooksCollection

Cbooks.create

Dbooks.createCollection

Attempts:

3 left

💡 Hint

Common Mistakes

Using create() method on a collection.

Confusing collection name with method name.

The correct method to create a collection explicitly is db.createCollection('books').

4fill in blank

hard

Fill both blanks to explicitly create a collection named 'employees' in the 'company' database.

MongoDB

use [1]
db.[2]('employees')

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

Acompany

Bemployees

CcreateCollection

Dstaff

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong database name.

Using wrong method to create collection.

First, switch to the 'company' database using use company. Then create the collection 'employees' explicitly with db.createCollection('employees'). Here, the blank for the method is createCollection.

5fill in blank

hard

Fill all three blanks to create a database 'library', create a collection 'books', and insert a document with title '1984'.

MongoDB

use [1]
db.[2].[3]({title: '1984'})

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

Alibrary

Bbooks

CinsertOne

DinsertMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using insertMany when only one document is inserted.

Using wrong collection or database names.

First, switch to the 'library' database. Then use the 'books' collection. Finally, insert one document with insertOne method.

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