Why querying is essential in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find all documents in the collection.

MongoDB

db.collection.find([1])

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

A{}

B[]

Cnull

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using an empty array instead of an empty object.

Using null which does not work as a query filter.

Using an empty object {} as the query returns all documents in the collection.

2fill in blank

medium

Complete the code to find documents where age is 25.

MongoDB

db.collection.find({ age: [1] })

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

Atrue

B"25"

C{ $eq: 25 }

D25

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around 25, which makes it a string.

Using a query operator without the correct syntax.

Use the number 25 without quotes to match the age field exactly.

3fill in blank

hard

Fix the error in the query to find documents with name 'Alice'.

MongoDB

db.collection.find({ name: [1] })

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

AAlice

B"Alice"

C{ $eq: Alice }

D'Alice'

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around string values.

Using single quotes which may cause errors in some environments.

String values in MongoDB queries must be in double quotes.

4fill in blank

hard

Fill both blanks to find documents where age is greater than 30.

MongoDB

db.collection.find({ age: { [1]: [2] } })

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

A$gt

B30

C25

D$lt

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt instead of $gt.

Using a wrong number value.

The operator $gt means 'greater than', so { age: { $gt: 30 } } finds ages over 30.

5fill in blank

hard

Fill all three blanks to find documents where name starts with 'J' and age is less than 40.

MongoDB

db.collection.find({ name: { [1]: [2] }, age: { [3]: 40 } })

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

A$regex

B"^J"

C$lt

D$gt

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gt instead of $lt for age.

Not using regex correctly for name.

Use $regex with "^J" to match names starting with 'J', and $lt to find ages less than 40.