$or operator behavior in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find documents where the field 'status' is either 'A' or 'D'.

MongoDB

db.collection.find({ $or: [ { status: [1] }, { status: 'D' } ] })

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

A'C'

B'B'

C'A'

D'E'

Attempts:

3 left

💡 Hint

Common Mistakes

Using $or without an array.

Using incorrect quotes or missing quotes around string values.

The $or operator requires an array of conditions. Here, we want documents where status is 'A' or 'D'. So the first condition must be { status: 'A' }.

2fill in blank

medium

Complete the code to find documents where 'age' is less than 30 or 'score' is greater than 80.

MongoDB

db.collection.find({ $or: [ { age: { $lt: [1] } }, { score: { $gt: 80 } } ] })

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

A30

B25

C35

D40

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gt instead of $lt for age.

Using a wrong number for comparison.

The condition is age less than 30, so $lt must be 30.

3fill in blank

hard

Fix the error in the query to correctly find documents where 'type' is 'book' or 'author' is 'John'.

MongoDB

db.collection.find({ $or: [ { type: 'book' }, { author: [1] } ] })

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

AJohn

B[ 'John' ]

C{ 'John' }

D'John'

Attempts:

3 left

💡 Hint

Common Mistakes

Using an object instead of an array for $or.

Not quoting string values.

The $or operator requires an array of conditions, not an object. The value for author should be a string 'John'.

4fill in blank

hard

Fill both blanks to find documents where 'category' is 'fiction' or 'year' is greater than 2010.

MongoDB

db.collection.find({ $or: [ { category: [1] }, { year: { $[2]: 2010 } } ] })

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

A'fiction'

Blt

Cgt

D'non-fiction'

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt instead of $gt for year.

Not quoting string values for category.

The first condition checks if category equals 'fiction'. The second condition uses $gt (greater than) for year > 2010.

5fill in blank

hard

Fill all three blanks to find documents where 'status' is 'active', or 'score' is at least 90, or 'age' is less than 25.

MongoDB

db.collection.find({ $or: [ { status: [1] }, { score: { $[2]: [3] } }, { age: { $lt: 25 } } ] })

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

A'active'

Bgte

C90

D'inactive'

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gt instead of $gte for score.

Not quoting string values for status.

The first condition checks status 'active'. The second uses $gte (greater than or equal) with 90 for score. The third checks age less than 25.