MongoDB Query API

The MongoDB Query API allows you to retrieve specific data from a MongoDB database based on various criteria.
This tutorial will provide an overview of the MongoDB Query API and cover different scenarios for querying data.

1. Basic Queries

Basic queries allow you to retrieve documents from a collection based on simple criteria.

Example:

db.collection.find({ key: value })

This query retrieves documents from the specified collection where the specified key matches the provided value.

2. Comparison Operators

MongoDB provides various comparison operators to perform more complex queries.

Examples:

db.collection.find({ age: { $gt: 30 } })

db.collection.find({ price: { $lt: 100 } })

These queries retrieve documents where the age is greater than 30 and the price is less than 100, respectively.

3. Logical Operators

Logical operators allow you to combine multiple conditions in a query.

Examples:

db.collection.find({ $and: [{ key1: value1 }, { key2: value2 }] })

db.collection.find({ $or: [{ key1: value1 }, { key2: value2 }] })

These queries use the $and and $or operators to retrieve documents that match both conditions or either condition, respectively.

4. Array Queries

MongoDB supports queries on arrays to find documents based on array elements.

Example:

db.collection.find({ tags: "mongodb" })

This query retrieves documents where the "tags" array contains the element "mongodb".

5. Projection

Projection allows you to specify which fields to include or exclude in query results.

Example:

db.collection.find({}, { _id: 0, name: 1 })

This query retrieves documents and includes only the "name" field while excluding the "_id" field.

6. Sorting

You can sort query results based on one or more fields.

Example:

db.collection.find().sort({ field: 1 })

This query sorts documents in ascending order based on the specified field.

7. Limit and Skip

Limit and skip allow you to control the number of documents returned and skip a certain number of documents.

Example:

db.collection.find().limit(10).skip(5)

This query returns 10 documents after skipping the first 5 documents.

8. What's Next?

Now that you've learned about the MongoDB Query API, you can efficiently retrieve and manipulate data from your MongoDB databases.

Explore more advanced query techniques, such as aggregation and indexing, to further enhance your MongoDB querying skills.

Archive