Quiz: Mastering MongoDB Query and Aggregation Practices Quiz

1. Basic Document Retrieval

   Which query will find all documents in the 'users' collection where the 'age' field is greater than 30?

   1. { age: { $gt: 30 } }
   2. { age: { $lt: 30 } }
   3. { age: { $gte: 30 } }
   4. { age: { $eq: 30 } }
   5. { 'age' u003E 30 }

2. Updating Multiple Fields

   How would you correctly update both the 'name' and 'email' fields for a single document using the updateOne method?

   1. { $set: { name: 'Sam', email: 'sam@example.com' } }
   2. { set: { name: 'Sam', email: 'sam@example.com' } }
   3. { $update: { name: 'Sam', email: 'sam@example.com' } }
   4. { $set: [ name: 'Sam', email: 'sam@example.com' ] }
   5. { $modify: { name: 'Sam', email: 'sam@example.com' } }

3. Logical Query Operators

   Which operator is used in MongoDB to combine multiple conditions with a logical AND?

   1. $and
   2. $or
   3. $not
   4. u0026and
   5. $nand

4. Using Aggregation Framework

   Which aggregation stage allows you to group documents by a specified field and perform accumulations like sum or average?

   1. $group
   2. $sort
   3. $project
   4. $limit
   5. $concat

5. Querying Embedded Documents

   How would you find documents where the 'address.city' field equals 'London'?

   1. { 'address.city': 'London' }
   2. { address.city = 'London' }
   3. { address: { city: 'London' } }
   4. { address_city: 'London' }
   5. { 'address-city': 'London' }

6. Array Field Matching

   If you want to find documents with at least one element in the 'tags' array equal to 'active', which query do you use?

   1. { tags: 'active' }
   2. { tags: { $eq: ['active'] } }
   3. { tags: { $contains: 'active' } }
   4. { $in: { tags: 'active' } }
   5. { tags: { $equals: 'active' } }

7. Aggregation Sorting

   Which aggregation stage is used to sort the output documents by a particular field in descending order?

   1. { $sort: { field: -1 } }
   2. { $order: { field: -1 } }
   3. { $sortBy: { field: -1 } }
   4. { $descending: { field: 1 } }
   5. { $orderby: { field: -1 } }

8. Field Renaming in Aggregation

   Which aggregation operator allows you to change field names or include/exclude fields in documents?

   1. $project
   2. $rename
   3. $update
   4. $replace
   5. $modify

9. Querying for Null Values

   How would you retrieve documents in the 'order' collection where the field 'deliveryDate' is missing or set to null?

   1. { deliveryDate: null }
   2. { deliveryDate: { $null: true } }
   3. { deliveryDate: { $isNull: true } }
   4. { deliveryDate = NULL }
   5. { deliveryDate: undefined }

10. Updating Array Elements

    Which update operator is used to add an item to an array field within a document?

    1. $push
    2. $add
    3. $append
    4. $inc
    5. $arrayAdd