MongoDB
5 min read
MongoDB is a popular NoSQL database that is document-oriented and designed for scalability and flexibility. You can work with MongoDB in a GUI with MongoDB Compass.
Docker-Compose
yml
version: '3'
services:
mongo:
image: mongo
restart: always
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: password
volumes:
- ./db:/data/db
ports:
- "27017:27017"
Usage
Connecting to MongoDB
To connect to MongoDB using the mongo shell: mongo mongodb://<username>:<password>@<hostname>:<port>/<database>
Replace <username>, <password>, <hostname>, <port>, and <database> with your own values.
Working with Databases
To create a new database: use <database> To show a list of all databases: show dbs To switch to a different database: use <database> To drop a database: use <database>; db.dropDatabase()
Working with Collections
To create a new collection: db.createCollection("<collection>") To show a list of all collections in the current database: show collections To drop a collection: db.<collection>.drop()
Inserting Data
To insert a single document: db.<collection>.insertOne(<document>) To insert multiple documents: db.<collection>.insertMany([<document1>, <document2>, ...])
Querying Data
To find all documents in a collection: db.<collection>.find() To find documents that match a specific condition: db.<collection>.find(<query>) To limit the number of documents returned: db.<collection>.find().limit(<limit>) To sort documents by a field: db.<collection>.find().sort({<field>: <1 or -1>}) To count the number of documents: db.<collection>.count()
Updating Data
To update a single document: db.<collection>.updateOne(<filter>, <update>) To update multiple documents: db.<collection>.updateMany(<filter>, <update>) To replace a document: db.<collection>.replaceOne(<filter>, <replacement>)
Deleting Data
To delete a single document: db.<collection>.deleteOne(<filter>) To delete multiple documents: db.<collection>.deleteMany(<filter>) To delete all documents in a collection: db.<collection>.deleteMany({})
Filters
Usage:
json
{ "field": { "$mod": "value" } }
• $eq: The $eq operator matches documents where the value of a field equals a specified value.
• $ne: The $ne operator matches documents where the value of a field is not equal to a specified value.
• $gt: The $gt operator matches documents where the value of a field is greater than a specified value.
• $gte: The $gte operator matches documents where the value of a field is greater than or equal to a specified value.
• $lt: The $lt operator matches documents where the value of a field is less than a specified value.
• $lte: The $lte operator matches documents where the value of a field is less than or equal to a specified value.
• $in: The $in operator matches documents where the value of a field equals any value in a specified array.
• $nin: The $nin operator matches documents where the value of a field does not equal any value in a specified array.
• $and: The $and operator performs a logical AND operation on an array of two or more expressions and selects the documents that satisfy all the expressions.
• $or: The $or operator performs a logical OR operation on an array of two or more expressions and selects the documents that satisfy at least one of the expressions.
• $not: The $not operator performs a logical NOT operation on the specified expression and selects the documents that do not match the expression.
• $regex: The $regex operator matches documents where a specified field matches a regular expression.
• $text: The $text operator performs a text search on the specified field(s).
• $elemMatch: The $elemMatch operator matches documents where a specified array field contains at least one element that matches all the specified conditions.
• $size: The $size operator matches documents where a specified array field has a specific size.
• $exists: The $exists operator matches documents that contain or do not contain a specified field, including documents where the field value is null.
Example:
js
db.users.find(
{
$and: [
{ status: "active" },
{ age: { $gt: 28 } }
]
}
)
Update Modifiers
• $set: The $set operator updates the value of a field in a document.
• $unset: The $unset operator removes a field from a document.
• $inc: The $inc operator increments the value of a field in a document.
• $mul: The $mul operator multiplies the value of a field in a document.
• $min: The $min operator updates the value of a field in a document if the new value is lower than the existing value.
• $max: The $max operator updates the value of a field in a document if the new value is higher than the existing value.
• $rename: The $rename operator renames a field in a document.
• $addToSet: The $addToSet operator adds a value to an array field in a document if the value does not already exist in the array.
• $push: The $push operator appends a value to an array field in a document.
• $pull: The $pull operator removes a value from an array field in a document.
• $currentDate: The $currentDate operator sets the value of a field in a document to the current date and time.
• $each: The $each¥ operator can be used with $addToSet and $push to append multiple values to an array field in a document.
• $sort: The $sort operator can be used with $push to sort the elements in an array field in a document.
Example:
js
db.users.updateOne(
{ name: "John Doe" },
{
$set: { age: 35 },
$addToSet: { interests: "Hiking" },
$unset: { status: "" }
}
)