Why query operators are needed in MongoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find documents where age is greater than 25.

MongoDB

db.users.find({ age: { [1]: 25 } })

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

A$gt

B$lt

C$eq

D$ne

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt instead of $gt will find ages less than 25.

Using $eq will find ages exactly 25, not greater.

The $gt operator means 'greater than'. It finds documents where the age is more than 25.

2fill in blank

medium

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

MongoDB

db.orders.find({ status: { [1]: ["A", "B"] } })

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

A$and

B$in

C$or

D$nin

Attempts:

3 left

💡 Hint

Common Mistakes

Using $or requires multiple conditions, not an array.

Using $nin finds documents NOT in the list.

The $in operator matches any value in the given array. It finds documents where status is 'A' or 'B'.

3fill in blank

hard

Fix the error in the query to find documents where score is less than or equal to 80.

MongoDB

db.scores.find({ score: { [1]: 80 } })

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

A$gte

B$lt

C$lte

D$eq

Attempts:

3 left

💡 Hint

Common Mistakes

Using $lt finds scores strictly less than 80, excluding 80.

Using $gte finds scores greater than or equal to 80.

The $lte operator means 'less than or equal to'. It finds scores 80 or below.

4fill in blank

hard

Fill both blanks to find documents where price is greater than 50 and less than 100.

MongoDB

db.products.find({ price: { [1]: 50, [2]: 100 } })

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

A$gt

B$lt

C$gte

D$lte

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gte or $lte changes the range to include 50 or 100.

Swapping the operators will cause wrong results.

Use $gt for 'greater than 50' and $lt for 'less than 100' to find prices between 50 and 100.

5fill in blank

hard

Fill all three blanks to find documents where age is at least 18, less than 65, and status is 'active'.

MongoDB

db.users.find({ age: { [1]: 18, [2]: 65 }, status: [3] })

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

A$gte

B$lt

C"active"

D"inactive"

Attempts:

3 left

💡 Hint

Common Mistakes

Using $gt instead of $gte excludes age 18.

Using $lte includes age 65, which is not wanted.

Setting status to 'inactive' returns wrong documents.

Use $gte for 'age at least 18', $lt for 'age less than 65', and set status to the string 'active'.