Why advanced stages matter 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.[1]()

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

Afind

Bupdate

Cinsert

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'insert' instead of 'find' will add data, not retrieve it.

Using 'update' or 'delete' changes or removes data, not fetches it.

The find() method retrieves all documents from a MongoDB collection.

2fill in blank

medium

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

MongoDB

db.collection.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' will find ages less than 25, not greater.

Using '$eq' looks for exactly 25, not greater.

Using '$ne' finds ages not equal to 25.

The $gt operator means 'greater than' in MongoDB queries.

3fill in blank

hard

Fix the error in the aggregation pipeline to group by 'category'.

MongoDB

db.collection.aggregate([{ $group: { _id: "$ [1]" } }])

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

ACategory

Bcategory

Ccat

Dcategories

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'categories' or 'Category' will not match the field.

Using 'cat' is not the correct field name.

The field name must exactly match the document field, which is 'category'.

4fill in blank

hard

Fill both blanks to project only the 'name' and 'score' fields in the output.

MongoDB

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

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

Aname

Bscore

Cage

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Including fields like 'age' or 'address' will show unwanted data.

Leaving out fields will exclude them from the output.

Projection specifies which fields to include. Here, 'name' and 'score' are included.

5fill in blank

hard

Fill all three blanks to update the 'status' field to 'active' for documents where 'age' is less than 30.

MongoDB

db.collection.updateMany({ age: { [1]: 30 } }, { [2]: { [3]: "active" } })

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

A$lt

B$set

Cstatus

D$gt

Attempts:

3 left

💡 Hint

Common Mistakes

Using '$gt' will select ages greater than 30, which is wrong.

Using wrong update operators will cause errors or no changes.

Misspelling the field name 'status' will fail the update.

The query uses $lt to find ages less than 30, then $set to update the 'status' field to 'active'.