a step-by-step guide to learning MongoDB with code examples:
- Installation: To get started with MongoDB, you need to install it. You can download and install the MongoDB Community Server from the official website. Once you have installed MongoDB, you can start the MongoDB server by running the following command in your terminal:
mongodb
- Creating a Database: In MongoDB, you can create a database using the
use
command. If the database does not exist, MongoDB will create it for you:
use mydatabase
- Creating a Collection: A collection is a group of related documents in MongoDB. You can create a collection using the
db.createCollection()
method:
db.createCollection('mycollection')
- Inserting Documents: You can insert a new document into a collection using the
insertOne()
method:
db.mycollection.insertOne({
name: 'John Doe',
age: 30,
email: 'john.doe@example.com'
})
In this example, a new document with the fields name
, age
, and email
is inserted into the mycollection
collection.
- Querying Documents: You can query documents in a collection using the
find()
method:
db.mycollection.find()
This will return the first document in the mycollection
collection where the name
field is equal to “John Doe”.
- Updating Documents: You can update a document in a collection using the
updateOne()
method:
db.mycollection.updateOne(
{ name: 'John Doe' },
{ $set: { age: 35 } }
)
In this example, the document where the name
field is equal to “John Doe” is updated to set the age
field to 35.
- Deleting Documents: You can delete a document from a collection using the
deleteOne()
method:
db.mycollection.deleteOne({ name: 'John Doe' })
In this example, the document where the name
field is equal to “John Doe” is deleted from the mycollection
collection.
- Aggregation: Aggregation operations process data records and return computed results. You can use the
aggregate()
method to perform aggregation operations:
db.mycollection.aggregate([
{ $group: { _id: '$name', total: { $sum: '$age' } } }
])
In this example, the aggregate()
method groups the documents in the mycollection
collection by the name
field and computes the total of the age
field for each group.
- Indexes: Indexes can be used to improve query performance. You can create an index using the
createIndex()
method:
db.mycollection.createIndex({ name: 1 })
In this example, an index is created on the name
field of the mycollection
collection.