Which MongoDB questions to prepare for practice?

MongoDB Questions to Prepare for Practice

Practicing MongoDB questions helps in mastering its core concepts, query language, and real-world problem-solving skills. Below is a categorized list of questions for effective preparation.

1. Basic CRUD Operations

• How do you create a database and a collection in MongoDB?
• Write a query to insert one and multiple documents into a collection.

  db.collection.insertOne({ name: "Alice", age: 25 });
  db.collection.insertMany([{ name: "Bob" }, { name: "Charlie" }]);

• How do you retrieve all documents from a collection?
• Write a query to update a specific field in a document.

  db.collection.updateOne({ name: "Alice" }, { $set: { age: 26 } });

• How do you delete a document where a field matches a value?

2. Querying and Filtering

• Retrieve all documents where a field value matches a specific condition.

  db.collection.find({ age: { $gt: 25 } });

• How do you project specific fields in the result set?

  db.collection.find({}, { name: 1, age: 1 });

• Write a query using the $regex operator to find documents where a field starts with "A."
• How do you sort documents in ascending and descending order?

3. Aggregation Framework

• Write a query to group documents by a specific field and count the occurrences.

  db.collection.aggregate([{ $group: { _id: "$age", count: { $sum: 1 } } }]);

• Use the $match and $project stages in an aggregation pipeline.

  db.collection.aggregate([
    { $match: { age: { $gt: 25 } } },
    { $project: { name: 1, age: 1 } }
  ]);

• Perform an aggregation query to find the average age of users.